Fungus Gnats

17 November 2008

Virginia Cooperative Extension, Charlottesville/Albemarle County Office
460 Stagecoach Road, Charlottesville, Virginia 22902
phone: 434.872.4580   fax: 434.872.4578

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With winter weather approaching many of us bring our tender plants indoors for the winter. With the plants we sometimes get their pests. When these insects have a little population explosion inside our homes it is not always greeted with the curiosity and wonderment you might expect. One common suspect in these situations is the fungus gnat.

A photo of a fungus gnat.

Fungus gnats occasionally become a nuisance indoors when adults emerge in large numbers from potted plants or flower boxes containing damp soil rich in humus. Adults are attracted to lights and are often first noticed at windows. The immature fungus gnats or maggots feed in soil high in organic matter and can injure the roots of bedding plants, African violets, carnations, cyclamens, geraniums, poinsettias and foliage plants. Plant symptoms may appear as sudden wilting, loss of vigor, poor growth, yellowing, and foliage loss. Some are serious pests in mushroom houses. Fungus gnats inhabit fungi or dead plant materials and are harmless to humans and animals.

Adult fungus gnats are about 1/8 to 1/10 inch (2.5 mm) long, grayish to black, slender, mosquito-like, and delicate with long legs, antennae and one pair of wings. Identification can be made by the vein patterns in the wings if you are the kind of person who enjoys examining insect wing venation under a microscope (I did not think so). Eggs are hardly visible, oval, smooth, shiny white and semi-transparent. Larvae or maggots are legless, thread-like, white, shiny blackheaded, up to 1/4 inch (5.5 mm) long and transparent so food in the gut can be seen through the body wall. Pupae occur in silk-like cocoons in the soil.

Fungus gnats reproduce in moist, shaded areas in decaying organic matter such as leaf litter. The life cycle is about four weeks, with continuous reproduction in homes or greenhouses where warm temperatures are maintained. Broods overlap, with all life stages present during the breeding season. Larvae not only feed on fungi and decaying organic matter, but on living plant tissue, particularly root hairs and small feeder roots. Brown scars may appear on the chewed roots. The underground parts of the stem may be injured and root hairs eaten off. Damage occurs most often in greenhouses or plant beds.

Adults live about 7 to 10 days and deposit eggs on the moist soil surface or in soil cracks. Females lay up to 100 to 300 eggs in batches of 2 to 30 each in decaying organic matter. Eggs hatch in 4 to 6 days; larvae feed for 12 to 14 days. The pupal stage is about 5 to 6 days. There are many overlapping generations throughout the year.

An ounce of prevention is worth a pound of cure as usual. Inspect plants carefully before purchase for signs of insect infestation. Always use sterile potting soil to prevent introduction of fungus gnats. Overwatering, water leaks, and poor drainage may result in buildup of fungus gnats. Allowing the soil to dry as much as possible, without injury to the plants, is effective in killing many maggots. Since houseplants taken outside during warm weather may become infested with insects before being brought back indoors is a good idea to inspect plants carefully and you may want to discard some if they are heavily infested. Remove all old plant material and debris in and around the home. Practice good sanitation.

Many counties offer Master Gardener Volunteer training beginning in the New Year. Contact your local Extension Office for more information on classes near you.

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For more information about this and other landscape topics contact your local Virginia Cooperative Extension office. The local Virginia Cooperative Extension office numbers are Albemarle 872-4580, Fluvanna 591-1950, Greene 985-5236, Louisa 540-967-3422, and Nelson 263-4035.

Crickets

13 October 2008

Virginia Cooperative Extension, Charlottesville/Albemarle County Office
460 Stagecoach Road, Charlottesville, Virginia 22902
phone: 434.872.4580   fax: 434.872.4578

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Feeling a little jumpy lately? Late summer and early fall are when cricket populations seem to be everywhere there is vegetation and sometimes in your house. This is not usually a problem for our landscapes as crickets are omnivorous and may eat anything from decaying vegetation to each other but most people do not like to find them where they live.

Cave Cricket.

Certain crickets are a pest merely by their presence and others because of their monotonous chirping when we are trying to get some sleep. In some countries, crickets have been kept as pets for thousands of years, valued for their chirping which may seem pleasant to some.

Indoors, some crickets can feed on a wide variety of fabrics, foods and paper products. Cotton, linen, wool, rayon, nylon, silk and furs are susceptible, along with soiled fabrics, sizing from wallpaper, glue from book bindings, fruit, vegetables, meat and even other crickets. An occasional cricket or two in the home usually presents no serious problem. However, large populations may congregate around lights at night, making places unattractive.

Crickets get their name from the high-pitched sound or “chirp” produced when the male rubs his front wings together to attract a female. Their songs can identify crickets, like birds, and there are commercially available sound recordings to help one quickly become an expert.

Crickets come in many shapes and sizes and are commonly categorized using basic characteristics. The True Crickets which include the house, field, ground, and tree crickets resemble long-horned grasshoppers in having long antennae, singing organs on the front wings of the male and hearing organs on the front legs.

House Cricket adults are about 3/4 to 7/8 inch long, straw-colored, with three dark bands on the head and have long, slender antennae much longer than the body. Wings lay flat on the back but are bent down abruptly on the sides. Females have a long, slender, tube-like structure projecting from their abdomen for egg laying.

Field Cricket adults range in size from 1/2 to 1-1/4 inches long depending on the species, are usually black-colored (sometimes brown), have long, slender antennae and a typical stout body (more robust than the house cricket) with large “jumping” hind legs. Most chirp and may sing both day and night.

Ground Cricket adults resemble house and field crickets but are much smaller, usually less than 1/2 inch long, and brownish. Their songs are often soft, high-pitched, pulsating trills or buzzes.

Snowy Tree Cricket adults are about 5/6 to 7/8 inch long and pale yellow or green. Male wings are broad, paddle-like, and lay flat on the back at rest, whereas the female forewing is narrow, and wrapped closely about the body. They chirp at a regular rate varying with the temperature. A good approximation of the temperature in degrees Fahrenheit is to add 40 to the number of chirps in 15 seconds. These are the crickets commonly heard in the background noises of TV and movies. Most deliver loud trills.

Camel Cricket adults, sometimes called cave or cellar crickets, are a little over 3/4 inch long, light tan to dark brown, wingless, with head bent downward, back arched in a humpbacked appearance, large hind legs, and long antennae.

There are special songs for courtship, fighting, and sounding an alarm. The principle role is to bring the sexes together with different songs in different species. Male crickets “sing” by rubbing a sharp edge called the scraper at the base of one front wing along a file-like ridge on the bottom side of the other front wing, resulting in a series of “chirps.” The number of chirps varies with the temperature with faster chirping at higher temperatures. Chirps vary from four to five to more than 200 per second. The song is amplified by the wing surface.

Crickets are usually active at night, prefer shelter in cracks and crevices, and invade homes seeking moisture. An occasional cricket or two in the home usually presents no serious problem. They are rarely serious pests in the home.

Sanitation is the most important means of eliminating nuisance crickets. Here are some tips.

• Keep all areas in and around buildings free of moisture, dense vegetation, and weeds.
• A one-foot band next to foundation will suffice.
• Mow lawns, cut weeds, and clean up garbage collection areas.
• Remove harborage sites such as piles of bricks, stones, rotting wood and other debris.
• Caulk and seal all cracks and crevices, especially near the ground level at basement windows and doorways.
• Make sure that all windows and doors are tight fitting with proper screening in place.
• Avoid bright mercury vapor lights in entryways and along structure perimeters since crickets will be attracted from far distances.
• Convert to sodium vapor yellow lights (less attractive to insects) instead of white, neon or mercury vapor lights.
• Never store firewood next to the house foundation.
• Raise garbage cans off the ground if practical.
• Trash and dumpsters should be placed as far from the building as possible. Crickets are attracted to food in these areas. Crickets may be troublesome at trash dumps, grassy roadsides, pasture fields and wooded areas that they use as breeding sites before entering structures.

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For more information about this and other landscape topics contact your local Virginia Cooperative Extension office. The local Virginia Cooperative Extension office numbers are Albemarle 872-4580, Fluvanna 591-1950, Greene 985-5236, Louisa 540-967-3422, and Nelson 263-4035.

Hornworms

28 July 2008

Virginia Cooperative Extension, Charlottesville/Albemarle County Office
460 Stagecoach Road, Charlottesville, Virginia 22902
phone: 434.872.4580   fax: 434.872.4578

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About this time of year many of us are finding insects eating in our vegetable gardens, most are welcome because they are eating each other and some not so much because they are after our prized crops. Some of the most recognized are the hornworms as they strip the leaves and fruit from our tomato plants.

A photo of the tomato hornworm.

Hornworms, the larvae of sphinx or hawk moths, are among the largest and most familiar caterpillars found in Virginia, some reaching lengths of three inches or more. Almost all have a dorsal horn on the eighth abdominal segment or back end, and hence their common name. The most widely recognized hornworms are those that feed on tomatoes – the tomato hornworm and the tobacco hornworm. Although these two insects are considered garden pests, the majority of the hornworm species found in Virginia are rarely observed and do not cause significant injury to plants. The large frass or poop of hornworms often reveals their presence in a tree or garden.

Hornworms are commonly encountered as they wander over the ground in search of pupation sites. Full-grown hornworm larvae migrate from their host plant and dig in loose soil where they pupate. Pupation occurs a few inches below the soil surface in a small chamber of packed earth. Pupae are typically brown, two inches or more in length, and many have a pronounced “snout” off the head end. Sometimes we find pupa while preparing our gardens for the next crop.

Adult stages of hornworms are heavy-bodied, strong flying insects known as sphinx or hawk moths. Many of these, including the tomato and tobacco hornworm moths, fly at night and are rarely observed except occasionally at porch lights. However, some day flying species are popularly known as “hummingbird moths”. These moths have a superficial resemblance to hummingbirds or bumblebees in flight while they feed from deep-lobed flowers. The species that fit this description include the snowberry clearwing (Hemaris diffinis), the hummingbird clearwing (Hemaris thsybe), and the whitelined sphinx (Hyles lineata).

Tomato Hornworms

The most familiar hornworms, those associated with tomatoes and related plants, are a complex of two species, the tomato hornworm (Manduca quinquemaculata), and the tobacco hornworm (Manduca sexta). Both species are pests in vegetable gardens. The caterpillars chew leaves, and plants can be rapidly defoliated. Fruits may also be chewed. Tomatoes are particularly susceptible to injury; but other related plants, such as peppers and potatoes, are occasionally infested.

The tomato hornworm has a dark green “horn” with black sides, while that of the tobacco hornworm is red. The caterpillars also are differentiated by the white striping along their sides. These form a series of V’s with tomato hornworms, while there are diagonal dashes on the tobacco hornworm. Occasional dark forms of the tomato hornworm larvae occur. The caterpillars of these are much darker than the normal green, although the adult moths differ little in appearance.

Many of the tomato and tobacco hornworms overwinter as pupae in the soil in the vicinity of previously infested gardens, typically emerging in late May and June. However, the adult moths are strong fliers that may travel long distances. Female moths lay large pearl-colored eggs on the upper surface of leaves. The young caterpillars hatch and feed on the plant for a month or more. They have tremendous appetites and consume large amounts of leaves as they grow older and larger. After feeding, they wander away from the plant and pupate in the soil.

Adult moths are identified by examining the hind wing which has two separate wavy bands next to the border on the tomato hornworm that are fused with the tobacco hornworm. The white marks on the abdomen of the tomato hornworm are also more angularly marked.

Control in Gardens

Tomato hornworms are easily controlled by garden insecticides (e.g., carbaryl, permethrin, spinosad). Depending on the size of your crop, examination of the foliage with patience (for they are difficult to see) and tossing them aside when you find them can be effective. Larvae tend to feed on the exterior parts of plants during shadier periods, near dusk and dawn, when they may also be more readily observed and destroyed. A biological control organism that is also highly effective and sold commonly is Bacillus thuringiensis (e.g., Dipel, Thuricide). Best of all there is a natural enemy of the hornworms; a braconid wasp (Cotesia congregata) lays dozens of eggs inside the larvae. The immature wasps eat their way out of the hornworms and pupate by spinning a cocoon on outside of the caterpillar body. If you find hornworms covered with these tiny cocoons you should leave them be so the wasps can complete their life cycle and live to sting another hornworm.

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For more information about this and other landscape topics contact your local Virginia Cooperative Extension office. The local Virginia Cooperative Extension office numbers are Albemarle 872-4580, Fluvanna 591-1950, Greene 985-5236, Louisa 540-967-3422, and Nelson 263-4035.

Emerald Ash Borer

21 July 2008

Virginia Cooperative Extension, Charlottesville/Albemarle County Office
460 Stagecoach Road, Charlottesville, Virginia 22902
phone: 434.872.4580   fax: 434.872.4578

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The emerald ash borer, a new invasive insect was found early this month in Fairfax County in the Herndon and Springfield areas. It is not the first time this creature has crossed into Virginia but this time it might be here to stay. The threat of these insects has existed ever since they became established in the Midwest in 2002. Despite careful monitoring efforts and warnings from local experts, these beetles are back. When in comes to invasive insects, always bet on the bug.

A photo of the emerald ash borer.

You can do our trees and forests a favor by trying to slow down this and other pests. Do not move firewood to use at your cabin, campsite or home. Instead, buy firewood locally from a seller close to your destination. Why not bring firewood with you? According to the Virginia Department of Agriculture and Consumer Services Office of Plant and Pest Services, native trees and forests in the U. S. are threatened by invasive insects and diseases that live in dead and dying wood. These devastating pests may be accidentally spread to new locations by campers, hunters, other outdoor enthusiasts and homeowners moving firewood from one location to another.

The emerald ash borer, (EAB), Agrilus planipennis Fairmaire, an invasive insect from Asia, is one example of a pest spread by moving firewood. The tiny emerald ash borer, named for its metallic green color, attacks ash trees with disastrous results. In its adult form, EAB consumes ash tree foliage and actually causes little damage. The real devastation comes from the larvae, which feed on the inner bark and disrupt the ability of an ash tree to transport water and nutrients.

The emerald ash borer was discovered in 2002 in southeastern Michigan and Windsor, Ontario. It infests and kills North American ash species (Fraxinus sp.) including green, white, black and blue ash. Damage is caused by the larvae, which feed in tunnels (called galleries) in the phloem just below the bark. The serpentine galleries disrupt water and nutrient transport, causing branches, and eventually the entire tree, to die. Adult beetles leave distinctive D-shaped exit holes in the outer bark of branches and the trunk. Adults are roughly 3/8 to 5/8 inch long with metallic green wing covers and a coppery red or purple abdomen. They may be present from late May through early September but are most common in June and July. There are other beetles that resemble the EAB but it is always good to ask someone to identify suspicious beetles when found.

EAB is responsible for over 20 million dead and dying ash trees in Michigan, Ohio, Indiana, and Illinois since its accidental introduction into the U. S. in 2002. The destruction has cost homeowners, landowners, the nursery and forest products industries, and government millions of dollars. Because there are no native predators of the emerald ash borer in North America, it is very difficult to control the spread once infestation takes place. Therefore, it is vital to block any opportunities for introducing the pest into new territory.

In 2003, Virginia had an alarming encounter with the emerald ash borer. When state officials determined that ash trees sent from a Michigan nursery and planted at an elementary school in Fairfax County, Virginia, were infested with EAB, it took the combined efforts of federal, state and county agencies to implement an eradication program. To prevent the spread of the insect, all ash trees within a half mile radius of the school were destroyed. Surveys taken by Virginia investigators for three consecutive seasons after the incident showed no new evidence of EAB in the state but now they are back.

For additional information about the emerald ash borer and actions taken to combat its spread, check out the following sites:

• http://www.fairfaxcounty.gov/dpwes/environmental/eab_general.htm
• http://www.emeraldashborer.info/
• http://www.aphis.usda.gov/plant_health/plant_pest_info/emerald_ash_b/index.shtml
• http://na.fs.fed.us/firewood/
• http://www.nps.gov/shen/planyourvisit/firewood_eab.htm

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For more information about this and other landscape topics contact your local Virginia Cooperative Extension office. The local Virginia Cooperative Extension office numbers are Albemarle 872-4580, Fluvanna 591-1950, Greene 985-5236, Louisa 540-967-3422, and Nelson 263-4035.

Assassin Bugs

23 June 2008

Virginia Cooperative Extension, Charlottesville/Albemarle County Office
460 Stagecoach Road, Charlottesville, Virginia 22902
phone: 434.872.4580   fax: 434.872.4578

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Often when I teach people about insects I am asked what is my favorite insect. Although I have trouble choosing one over another because they are all so loveable I usually, when pressed, choose the assassin bugs as a group and the wheel bug as my favorite.

A photo of a wheelbug.

Assassin Bugs are in the order Hemiptera or Heteroptera (depending on which textbook you prefer) sometimes called the true bugs. This order also includes stink bugs, pirate bugs, and big-eyed bugs among others. All insects in this order share a few characteristics, including piercing-sucking mouthparts, and wings which are membranous at the tips, but hardened at the base.

Assassin bugs are in the family Reduviidae. Insects in this family are distinguished from other members of the order by their short, 3-segmented beaks (most true bugs have 4-segmented beaks). Assassin bugs are usually dark-colored, with combinations of gray, green, and black. Assassin bugs also have long, narrow heads.

Like all members of the true bugs, assassin bugs go through a simple metamorphosis with egg, nymph, and adult stages. In warm months, females lay eggs which are stuck in clusters to leaves and stems. After hatching, the wingless nymphs grow and molt 4 to 7 times (depending on the species) before becoming full-sized, winged adults. Adults are usually the overwintering stage. Most members of the family Reduviidae are predators. The nymphs and adults capture insects and other arthropods with their raptorial front legs, much in the same way that an avian raptor uses its talons to capture prey. Assassin bugs then use their sharp beaks to suck fluids from their victim. They also may inject a small amount of poison that paralyzes their prey, making it easier to handle.

Assassin bugs actively hunt for prey. In general, assassin bugs hunt on various types of vegetation, including trees, weeds, and bushes although they can be found on structures such as houses where insect prey, wasp nests for example, are found. Assassin bugs are able to fly, but they are poor fliers.

Although assassin bugs are fierce predators, they are sometimes eaten by birds, rodents, and large predatory arthropods, such as spiders, praying mantids, and even other assassin bugs. Assassin bugs are especially vulnerable to predation when they are in the nymph stage.

A few species in this family are parasites that feed on the blood of mammals. The bloodsucking conenose or kissing bug, Triatoma sanguisuga, is a common example. It normally feeds on rodents, but will sometimes bite humans that sleep near rodent nests. They are called kissing bugs because they often feed near your mouth.

As you might imagine, bugs in the family Reduviidae are considered pests when they bite humans. Common predatory assassin bugs, like the wheel bug, will occasionally inflict painful bites if you pick them up but they do not commonly attack humans except in defense. For the most part, assassin bugs have reputations as beneficial insects because they feed on other arthropods.

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For more information about this and other landscape topics contact your local Virginia Cooperative Extension office. The local Virginia Cooperative Extension office numbers are Albemarle 872-4580, Fluvanna 591-1950, Greene 985-5236, Louisa 540-967-3422, and Nelson 263-4035.

Asian Ambrosia Beetle

9 June 2008

Virginia Cooperative Extension, Charlottesville/Albemarle County Office
460 Stagecoach Road, Charlottesville, Virginia 22902
phone: 434.872.4580   fax: 434.872.4578

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As spring weather brings our plants back into action it also inspires insects to get back to work. Often we discover insects damaging plants in the spring when trees or shrubs fail to leaf out or wilt and drop their leaves soon after leafing out.

A photo of Asian Ambrosia Beetle Damage.

One striking example of this is the evidence seen from the feeding of the Asian ambrosia beetle. The toothpick-like tubes excavated by these beetles are diagnostic for their presence.

The Asian ambrosia beetle was first detected in the U.S. when it infested peach trees in Charleston, South Carolina in 1974. Since then it has spread to other parts including Virginia.

Toothpick-like spines protruding up to 1.5 inches from the host plant can identify infestations. The spines are strings of boring dust produced by the female beetle as she excavates her gallery. The spines are fragile and are easily broken off by wind or rain. Individual plants may host from one to more that 50 individual beetles. Although adults can be captured most of the year, trap data indicate they are most active during early spring.

The Asian ambrosia beetle is a small, but deadly-to-trees insect. It has a wide host range of trees, mainly infesting small diameter, smooth bark sections of trees. Peach, pecan and plum orchards have been attacked, as well as nursery tree stock. Other known hosts include cherry, persimmon, golden rain tree, sweet gum, Chinese elm, magnolia, fig, and Mexican buckeye. The ambrosia beetle is showing up in a wider range of plant material. We found them in London plane, river birch, zelkova, dogwood, sugar maple, sweet bay magnolia, and Styrax.

Females bore into twigs, branches, or small trunks of susceptible woody plants, excavate a system of tunnels in the wood or pith, introduce the symbiotic ambrosial fungus, and produce a brood. Like other ambrosia beetles, they feed on ectosymbiotic fungi which they introduce into their tunnels and cultivate and not the wood and pith of their hosts. Eggs, larvae, and pupae are found together in the tunnel system excavated by the female. There are no individual egg niches, larval tunnels, or pupal chambers. It breeds in host material from 2 to 30 cm in diameter, although small branches and stems are most commonly attacked. Attacks may occur on apparently healthy, stressed, or freshly cut host material. High humidity is required for successful reproduction. Attacks on living plants usually are near ground level on saplings or at bark wounds on larger trees. Females remain with their brood until maturity. Males are rare, reduced in size, and flightless. Females mate with their brother(s) before emerging to attack a new host.

The beetles of the first generation are in the larval stage at this time. You can apply Onyx or Astro now to try and control the second generation that will come out at the end of June. There will already be damage from the first generation of beetles.

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For more information about this and other landscape topics contact your local Virginia Cooperative Extension office. The local Virginia Cooperative Extension office numbers are Albemarle 872-4580, Fluvanna 591-1950, Greene 985-5236, Louisa 540-967-3422, and Nelson 263-4035.

Carpenter Bees

2 June 2008

Virginia Cooperative Extension, Charlottesville/Albemarle County Office
460 Stagecoach Road, Charlottesville, Virginia 22902
phone: 434.872.4580   fax: 434.872.4578

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If you are seeing large, black and yellow bees hovering around the eaves, decks, and wood siding of your home you may be hosting some of our beneficial pollinators. Many of these are carpenter bees setting up housekeeping. Although they can pollinate our flowers, carpenter bees can cause cosmetic and structural damage to wood as well. They can also be quite intimidating to homeowners and have the potential to inflict painful stings.

A photo of a carpenter bee.

Carpenter bees are similar in appearance to bumblebees but differ in that they have a black, shiny tail end or abdomen while the bumble bee abdomen is covered with hair. You may remember the difference by thinking carpenters keep their tools clean and shiny. These bees also differ in their nesting habits. Bumblebees nest in the ground, whereas carpenter bees tunnel into wood to lay their eggs. Common nesting sites include eaves, fascia boards, siding, wooden shake roofs, decks, and outdoor furniture. The nest entrance holes are usually found on the underside of a board. Bare, unpainted, or weathered softwoods are preferred, especially redwood, cedar, cypress and pine. Painted and treated woods are less preferred, but they are not immune to attack.

The entrance hole and tunnels are perfectly round and about the diameter of a dime. Coarse sawdust, the color of fresh cut wood, is often seen beneath the entry hole, and burrowing sounds may be heard within the wood. Female carpenter bees may excavate new tunnels or enlarge and reuse old ones. Serious damage can result when the same piece of wood is utilized for nesting year after year until it looks like a Swiss cheese. The holes start upward (or inward) about 1/2 inch, then turn horizontally with the wood grain and may run six to seven inches or more. Occasionally, several bees may use the same entrance hole and have individual branches off the main tunnel. If the same entrance hole is used for several years, tunnels may extend several feet in the wood.

Carpenter bees overwinter as adults in old nest tunnels and emerge in the spring, usually in April or May. After mating, the fertilized females excavate tunnels in wood, laying their eggs within a series of small cells. The cells are provisioned with a ball of pollen on which the larvae feed. Additional cells are similarly provisioned until the tunnel is completely filled, usually with six to seven cells. Males do not drill tunnels, but they are territorial and will harass other bees and people who venture near their protected areas. The males, which can be distinguished from females by a whitish spot on the front of the face, do not sting. Females are capable of stinging, but rarely do so unless confined in your hand or are highly agitated. These adult bees die in a matter of weeks. The eggs hatch in a few days and the offspring complete their development in about 5 to 7 weeks. Adults begin to emerge in late summer. Although the bees remain active, feeding on pollen the general area, they do not construct new tunnels. With the onset of cold weather, the bees seek overwintering shelter.

The best time to control carpenter bees is before the tunnels are fully constructed. Treating the entrance holes with an insecticidal spray or dust may substantially reduce nesting activity. Be sure to read the pesticide label before buying or applying to make sure you have the right product and to understand how to apply it safely. Leave the holes open for a few days after treatment to allow the bees to contact and distribute the insecticide throughout the nest galleries. Then plug the entrance hole with a piece of wooden dowel coated with wood glue, wood putty, or other suitable sealant. This will protect against future use of the old nesting tunnels, as well as moisture intrusion and wood decay. The insecticide treatment is intended to kill both the adult bee and its offspring as they emerge later. Plugging untreated tunnels with wire mesh or similar material might trap bees inside, but more resourceful bees will simply chew another exit hole. Aerosol sprays sold for wasp or bee management are also effective and are often more convenient than dusts. Although carpenter bees are less aggressive than wasps, female bees provisioning their nests will sting. Treatment is best performed at night or while wearing protective clothing.

The initial appearance of carpenter bees in both the spring and summer is difficult to predict and their activity continues for several weeks. Preventive sprays applied to wood surfaces are effective only for a short period, meaning that you would have to repeat the application about every 2-3 weeks. Since virtually any exposed wood on the house is subject to attack, it is difficult (and usually not practical or safe) to try to protect all of the possible sites where the bees might tunnel. Spraying bees seen hovering around is not a sensible use of pesticides either. Since these bees are not aggressive and they do contribute to the pollination of our plants it would be best to learn to live with them as much as possible.

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For more information about this and other landscape topics contact your local Virginia Cooperative Extension office. The local Virginia Cooperative Extension office numbers are Albemarle 872-4580, Fluvanna 591-1950, Greene 985-5236, Louisa 540-967-3422, and Nelson 263-4035.

Ticks

5 May 2008

Virginia Cooperative Extension, Charlottesville/Albemarle County Office
460 Stagecoach Road, Charlottesville, Virginia 22902
phone: 434.872.4580   fax: 434.872.4578

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Landscape gardening is not without pitfalls. While we are mostly looking to protect our plants from problems sometimes we need to look out for ourselves. Poison ivy and mosquitoes are troublesome but nothing seems to put the fear of nature into most folks like the site of a tick crawling on your body. This fear is justified as ticks can carry dangerous diseases. A little knowledge can go a long way to preventing ticks from becoming serious problems.

A photo of a lonestar tick.

The four most common ticks in Virginia that are encountered by humans are the lone star tick, the American dog tick, the brown tick, and the blacklegged tick or deer tick as it is sometimes called. The lone star tick is found predominately east of the Blue Ridge Mountains. The American dog tick is found predominately west of the Blue Ridge Mountains. The brown dog tick can be found throughout Virginia but tends to be uncommon. The blacklegged tick is uncommon also and is found primarily in the northern and eastern sections of Virginia.

The brown dog tick is not known to carry any disease in Virginia. Both the lone star tick and the American dog tick are potential carriers of Rocky Mountain Spotted Fever. The blacklegged tick is a potential vector of Lyme disease and has been implicated in the transmission of ehrlichiosis. In any case of suspected tick transmitted disease, consult with a physician.

A tick needs to be attached for four to six hours in order to transmit Rocky Mountain Spotted Fever to its human host. The first symptoms noticed are usually severe headache, chills, fever, muscle aches, nausea, vomiting, and other flu-like symptoms. These first symptoms usually start 2 to 12 days after the tick bite. By the third day after the bite, a red rash develops on the wrists and ankles, in most cases, and often spreads to the entire hand or foot. A blood test is needed to confirm the disease, and early use of antibiotics has a very high rate of cure.

Lyme disease initially develops as an oblong rash, usually 2 or more inches in size, with a clear center that develops at the site of the tick bite, although only 70% of people develop this symptom. At a later time people usually develop flu-like symptoms such as nausea, headache, fever, and general stiffness of the neck joints. Chronic symptoms of a small percentage of untreated people include arthritis and nervous system complications.

All ticks have eight legs in the adult stage, but have six legs as newly hatched larvae. Small ticks of all species are called seed ticks, a common name that does not refer to one particular species. The American dog tick is about 5 mm long with short stout mouthparts. It is dark brown with light wavy lines or reticulations on its back. The lone star tick is about 5 mm in length or less with long mouthparts. It is light reddish-brown with a central white spot on the back of most of the adults. The brown dog tick is about 5 mm long with short stout mouthparts. It is distinguished from the American dog tick by its dark reddish-brown color and lack of any white markings. The blacklegged tick is a small tick about 2-3 mm in length with long mouthparts. It is off-white or reddish when fed and has black legs.

Ticks pass through three feeding stages: the larva, nymph, and adult. Typically, each stage feeds on a different host. Hosts include a variety of animals (e.g., mice, rabbits, and deer), and each stage of the tick has a different host depending on the life stage. Humans are accidental hosts that are not part of the natural life cycle of the tick. After feeding on a host, a tick becomes engorged with blood and drops from the host. Once in a protected place, immature ticks molt to the next stage, and adult females produce eggs after their final blood meal.

The Virginia Department of Health recommends the following methods of prevention.

• Avoid tick-infested areas such as tall grass and dense vegetation
• Walk in the center of trails and avoid brushing against weeds and tall grass
• Keep grass and underbrush cut and thinned
• Wear light colored clothing so ticks can be found easily
• Tuck pant legs into socks so ticks stay on the outside of pants.
• Conduct tick checks on children and pets every 4 hours
• Keep pets outside from April to September to help keep ticks out of the house
• Use tick repellents that contain 10 to 30% DEET (not recommended for infants or pregnant people)
• Ask your veterinarian to recommend tick controls for your pets

Ticks are best removed with tweezers or by wrapping the tick in tissue paper and pulling out with fingers. Do not twist or jerk, and pull slowly to avoid leaving the mouthparts in the wound. Do not use nail polish, petroleum jelly, alcohol, or hot matches to remove the tick. Wash the wound with an antiseptic after the tick is removed. Kill the tick in rubbing alcohol and keep it in a small vial for a few months in case any disease symptoms develop.

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For more information about this and other landscape topics contact your local Virginia Cooperative Extension office. The local Virginia Cooperative Extension office numbers are Albemarle 872-4580, Fluvanna 591-1950, Greene 985-5236, Louisa 540-967-3422, and Nelson 263-4035.

Lace Bugs

21 April 2008

Virginia Cooperative Extension, Charlottesville/Albemarle County Office
460 Stagecoach Road, Charlottesville, Virginia 22902
phone: 434.872.4580   fax: 434.872.4578

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There are a variety of lace bugs in our environment and they feed on many of our ornamental trees and shrubs including azalea, rhododendron, sycamore, broad-leaved evergreens, and others. In the spring we may notice symptoms and signs from these insects from last year and this is a good opportunity to plan for the coming season.

A drawing of an azalea lace bug adult and nymph respectively.

Description

Lace bug damage is usually first noticed as yellow spots on the upper leaf surfaces of affected plants. Lace bugs actually feed on the undersides of leaves with their piercing-sucking mouthparts, but because they kill surrounding cells as they feed, they cause yellow spots to appear on upper sides of the leaves. The first yellow spots that appear are very similar to mite damage, but the spots made by lace bugs are larger. When feeding damage becomes severe, the leaves take on a gray blotched appearance or can turn completely brown. As lace bugs feed they produce brown varnish-like droppings that spot the underside of the leaves. These droppings further distinguish lace bug damage from mite damage. When large numbers of lace bugs are present cast skins can often be found attached to the leaves where they molt.

Adult lace bugs are about 3 to 6 mm (1/8″- 1/4″) long with a netlike pattern on the wings. In addition, the wings are dotted with brown and black. The immature stages, called nymphs, are similar except they are smaller and often have spines. The eggs, although small, are easily distinguished by their elongate and cylindrical shape. They resemble small black smokestacks attached to the undersides of the leaf. Lace bugs are classified in a group we call true bugs and they are closely related to some of our other insect friends such as the stink bugs, squash bugs, and assassin bugs.

Lifecycle

On deciduous plants, adult lace bugs overwinter in protective places on the host, such as bark crevices and branch crotches, or on the ground in leaf litter. They end their hibernation just as spring growth starts. They attach their eggs to the undersides of the leaves often along the midribs, sometimes covering them with a black varnish-like coating. The eggs will stay attached to the leaves long after they have hatched and can be recognized by noting if the tops have openings. The nymphs complete their life cycles quickly and one to several generations can occur in one season; usually, there are two generations. Some lace bugs can complete a generation in as few as 30 days. Usually, by the end of the summer, all life stages can be found on a host.

On broad-leaved evergreens, lace bugs overwinter as eggs on the undersides of leaves. Eggs hatch in May in Virginia and two or more generations may occur during the growing season.

The azalea lace bug, Stephantis pyrioides (Scott), completes two generations in Virginia per year. The second brood builds up to high populations in August and September and damage can be severe. In some cases, the leaves turn completely brown and are heavily spotted with droppings by the end of the summer.

The hawthorn lace bug, Corythucha cydoniae (Fitch), selectively attacks a variety of woody, rosaceous plants and can cause severe leaf damage.  It has been reported on apple, button bush, cotoneaster, hawthorn, serviceberry, loquat, oak, pear, pyracantha, and quince.

Management

Lace bug control requires careful monitoring early in the season. The presence of beneficial insects may mean that chemical use can be avoided.  If chemicals are used treatments should be applied where insects are found on the foliage, either on adults on deciduous plants or on groups of nymphs on broadleaf evergreens. It is very important to spray the undersides of the leaves because this is where they feed. Control of the first generations is most important to slow population buildup.  Current control recommendations include the following chemicals.  Acephate (Orthene), carbaryl (Sevin), cyfluthrin, imidacloprid (Merit), malathion, methoxychlor, pyrethrins + PBO, and tetramethrin.  Consult the label for host plants and specific pests listed under directions for use and please use pesticides safely.

The common pattern we see is lace bug outbreaks on azaleas growing in landscapes that are structurally simple.  Structural complexity is a measure of the amount of vegetation at the various plant strata (such as overstory, understory, shrub, etc.). The more plant material within a landscape the less likely lace bugs will cause trouble.

It was originally believed that lace bug outbreaks were related to sun and shade.  The theory being that azaleas (which are truly understory shrubs) grown in the sun were stressed and therefore better food for lace bugs.  Studies found that this was not the case and that lace bugs performed better on foliage from shade grown azaleas.  Other studies found that natural enemies were the driving force in these outbreak patterns.  Structurally complex landscapes support a greater abundance and diversity of natural enemies than structurally simple landscapes.  One of these natural enemies is the green lacewing.  Green lacewings are native and common but can be purchased to augment a situation where lace bugs are a problem.

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For more information about this and other landscape topics contact your local Virginia Cooperative Extension office. The local Virginia Cooperative Extension office numbers are Albemarle 872-4580, Fluvanna 591-1950, Greene 985-5236, Louisa 540-967-3422, and Nelson 263-4035.

Carpenter Ants

14 April 2008

Virginia Cooperative Extension, Charlottesville/Albemarle County Office
460 Stagecoach Road, Charlottesville, Virginia 22902
phone: 434.872.4580   fax: 434.872.4578

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It is about this time of year that folks start seeing insects wandering around inside their houses. One of the more noticeable of these insects is the carpenter ant.

Carpenter ants eating sugar.

These chunky black (sometimes red and black) ants can range from one-quarter inch for worker ants up to three-quarters of an inch for the queen. Like all species of ants, carpenter ants have a constricted hourglass waist and elbowed antennae. These characteristics distinguish them from the thick-waisted termites with their straight antennae. Ants are closely related to bees, wasps, and sawflies.

Carpenter ants share at least one annoying habit with termites. They construct extensive nests in wood, including logs, stumps, tree trunks, telephone poles, and, unfortunately, buildings. Nests are usually begun in deteriorating wood that has been exposed to moisture. Often, the colony will extend its nest to adjacent, sound wood.

The colonies of carpenter ants are often long lived. A single fertilized queen founds each colony. She establishes a nesting site in a cavity in wood. She then rears her first brood of workers, feeding them salivary secretions. She does not leave the nest nor feed herself throughout this period. The workers who are reared first assume the task of gathering food with which to feed the younger larvae. As the food supply becomes more constant, the colony population grows very rapidly. A colony does not reach maturity and become capable of producing young queens and males until it contains 2,000 or more workers. It may take a colony from three to six years or more to reach this stage. Each year thereafter, the colony will continue to produce winged queens and males, which leave their nest and conduct mating flights in the spring and summer.

While termites actually eat and digest wood, carpenter ants simply chew and tunnel through it to build their homes. Carpenter ants rarely cause structural damage to buildings, although they can cause significant damage over a period of years because nests are so long lived. Damage by carpenter ants can leave household structural timber open to fungus, rots, and other forms of decay. Some recent evidence indicates that they can also cause extensive damage to foam insulation. If faced with chewing through hard wood or soft insulation to build your nest, which would you choose?

Finding carpenter ants indoors in the winter is an indication that they are nesting somewhere within the walls or floors of the building. This is due to the fact that carpenter ants, like all insects, are cold blooded. Ants active in the winter must be originating from a warmed source. Even if the air temperature outside is very cold, heat from the sun or your furnace or wood stove may warm your house walls and stir overwintering ants to activity. Ants found in the spring and summer are often invaders wandering in from outdoors looking for food or drink. In the spring, carpenter ants go through a mass-mating or swarming behavior. During this time carpenter ants raid houses looking for sweets, because one of their normal sources of sugar, the sweet honeydew from aphids, is not available until the weather warms up.

The critical factor in carpenter ant control is treating the nesting area. Locating the nest site is very rarely easy and there are times it may be impossible to locate the nest. The most likely sources of carpenter ants are window and door frames and sills, shower and tub enclosure walls, and kitchen and bath plumbing walls.

One of the goals of Integrated Pest Management and one of the reasons we encourage carpenter control by direct nest treatment is to limit the amount of pesticide applied. Oftentimes, we can get the ants to help out with the treatment.

Their love of sweets can be their downfall. One of the most effective ways to control carpenter ants is to set out poison baits. Attracted to the sweet taste, the worker ants collect the bait and bring it back to the colony, where they share it with the developing larvae and the queen.

It can be important to know what kind of ant you are dealing with since some ant species prefer different foods. Baits are formulated to work with certain species and will most likely specify which ones on the label.

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For more information about this and other landscape topics contact your local Virginia Cooperative Extension office. The local Virginia Cooperative Extension office numbers are Albemarle 872-4580, Fluvanna 591-1950, Greene 985-5236, Louisa 540-967-3422, and Nelson 263-4035.