September/October 2011

The Bug Report: Who's Eating What

By Anne Rowlands

Gardeners spend a lot of time with our insect friends and foes. Here's some information about who's eating what in gardens and woods across the state, and an urgent request for vigilance.

Rose Hiskes from The Connecticut Agricultural Experiment Station's (CAES) Department of Entomology and Carol Quish from UConn's Home & Garden Education Center contributed information about the season's most-reported insects, and Chris Maier at CAES was most helpful as well.

Other destructive insects have been reported this summer, such as the Asiatic Garden Beetle. Experts at UConn, the extension offices, and CAES are just a phone call or email away, and many excellent online resources can help you identify and deal with problem pests. (Links appear at the end of this article.)

MEET THE BEETLES

Viburnum Leaf Beetle -- Pyrrhalta viburni
Photo / Paul A. Weston, Cornell University, Bugwood.org

Viburnum Leaf Beetle (VLB)
Pyrrhalta viburni is an invasive alien that has been in this area in the nursery setting and is now on the increase in home gardens.

Life Cycle & ID
Adults of this leaf-feeding beetle are yellow to brown and approximately 0.25 inches long. During summer and fall the females make straight rows of cavities on the undersides of terminal twigs, lay multiple eggs in the cavities and cover them with a mixture of feces and shredded bark. The eggs spend the winter on the tips of the twigs, and flattened brown-spotted yellowish larvae hatch mid-May the following year and feed on the emerging leaves. About a month later, they crawl to the ground to pupate in the top 1 or 2 inches of soil. Adults emerge in three to four weeks (in July), feed, mate and begin laying eggs in the twigs. There is one generation each year.

Hosts & Damage
VLBs feed on foliage of thin-leaved viburnums (our natives, unfortunately, such as Viburnum opulus and V. dentatum) from July to September. Initial feeding by adults results in oval holes in leaves that can progress to total defoliation. Larval damage begins by skeletonizing leaves on the undersides, but as larvae increase in size, they begin to eat through the entire leaf, leaving only the veins.

Control
When noticed, larvae and adults can be handpicked. Twigs with eggs can be pruned off during the winter months when they are most visible. According to Rose Hiskes, neem-based products can be used to control small larvae and repel adults. Multiple applications are often necessary. Always consult the label for dosage rates and safety precautions, and follow them!

Probably the most important control measure for viburnum leaf beetle will be to plant species that are resistant to feeding by this pest. While at Cornell University, Dr. Paul A. Weston rated viburnums for tolerance to viburnum leaf beetle (www.hort.cornell.edu/vlb/index.html). Highly susceptible and susceptible species will die following approximately three successive years of defoliation.

Lily Leaf Beetele -- Lilioceris lilii
Photo / CAES

Lily Leaf Beetle
Lilioceris lilii is an exotic pest that's been in Connecticut since 1995. Both adults and larvae do serious damage to true lily plants. The heavy snow cover last winter helped protect adults, making for a bigger problem this season.

Life Cycle & ID
The 0.25 to .0375 inch long adult beetle has brilliant red wing covers with black legs, head, antennae and body. Adults overwinter in protected areas around the garden, often at the base of host plants. Beetles emerge over a few weeks in April and begin feeding as lilies break ground. Mating takes place in May and June. Females can lay up to 450 eggs over a period of several weeks from June into July. Eggs are laid only on true lilies, and rafts or rows of gelatinous yellow to brick-red eggs are found near the underside midrib on leaves. Eggs hatch in 7-10 days. Larvae are red-orange and sac-like but appear darker because of the feces they usually carry on their backs. The head is black. Larvae tend to feed gregariously on the underside of foliage. Often they'll feed from the tip of the leaf inward, and after mulching away for two to three weeks in July and August, mature larvae drop to the soil, burrow down and pupate. The 0.5 inch pupa, rarely seen because it's in the soil, is bright orange. New, bright red adults emerge 15-20 days later and feed on foliage until cold weather.

There is one generation per year. However, adults may live for two years. Adults appearing in the spring will be those that emerged the previous August along with second-year adults. As a result, adults may be present from April through October and it can seem that there is more than one generation per year.

Hosts & Damage
Leaves of all true lilies (Asiatic, Oriental, tiger lilies and hybrids) are eaten first. As the population grows, buds, flowers and stems are also eaten. Populations can build so quickly that entire plantings seem to disappear overnight. If not controlled when they are actively feeding, larvae will completely defoliate and ultimately kill all true lilies. Adults also will feed on Fritillaria, Polygonatum, Solanum, Smilax, Nicotiana and other plants, but are not able to complete their life cycle on these hosts. They do not feed on daylilies.

Control
As soon as lilies emerge in spring you can spot the scarlet red beetles. Handpicking is the best method of control. While wearing gloves (or with bare hands if you're not squeamish) and with soapy water at the ready in a quart container, carefully examine the underside of each leaf for adults, eggs and larvae. Squash everything you see and place in the soapy water. One method is to wet your fingers, put your thumb on the top of the leaf next to the stem and your forefinger on the underside, squeeze and pull everything into the soapy water container you're holding at the end of the leaf. (Be careful not to break off the tender tips of the plant when performing this maneuver). Adults have a defense mechanism of squeaking when they are lightly squeezed, so squeeze hard! The wily red adults, when disturbed, are likely to fall to the ground with their black bellies up, making them tough to spot. Try placing a light colored cloth under the plants when you start hand picking. Further reduce numbers by digging into the top half-inch of soil to expose any bright orange pupae or adults and dispatch them promptly.

If you are in an infested area, don't send lilies to others. Always inspect lilies or bulbs you buy or transplant. Azadirachtin (neem) will control small larvae and repel adults. Applications every 5-7 days after eggs hatch are necessary over a period of weeks. Spinosad spray kills larvae. Pyrethrin based products kill adults.

MOST WANTED -- REPORT IMMEDIATELY

Brown Marmorated Stink Bug -- Halyomorpha halys
Photo / Michael Thomas, CAES

Brown Marmorated Stink Bug (BMSB)
Halyomorpha halys is an exotic insect new to North America. This Asian native first entered Connecticut in 2008. It has now been reported in every county, and in 33 other states.

Life Cycle & Identification
Adults are mainly present in spring and in late summer to fall, when they seek shelter in houses and other protected places. They emerge from their overwintering sites in April. BMSBs are typically shaped stink bugs 0.5 to 0.75 inches long and are dark, mottled brown. The last two antennal segments have alternating broad light and dark bands. The exposed abdominal edges also have alternating dark and light banding. From June to August, females lay clusters of 20-30 light green, barrel-shaped eggs on the undersides of leaves. Newly hatched nymphs are yellowish mottled with black and red. Older nymphs are darker with banded legs and antenna, like the adults, and are active in the summer months.

Hosts & Damage
BMSBs enjoy a long list of host plants including many fruit trees, fruit, legumes and vegetables as well as other woody ornamentals. It feeds throughout the growing season, but adult feeding near harvest time is the most damaging. BMSB feeding can cause small necrotic areas on leaves and fruit, ranging from mild to severe. It injects an enzyme with its long snout and sucks up the slurry. Beetles can become a major nuisance when congregating in overwintering sites, invading houses and other buildings in a manner similar to Asian ladybird beetles and cluster flies. Plus, when disturbed, the bugs produce a characteristic pungent odor that adds to their nuisance potential.

Call to Action
According to Chris Maier, BMSB adults are adept hitchhikers, flying into box trucks, mail boxes, RVs, and other vehicles, which speed its spread. With its wide host range and the damage resulting from its feeding, BMSB has the potential to have a very tangible impact on agricultural crops, particularly those that are not normally treated for insect pests during the growing season. It has even damaged crops that are treated regularly with insecticides.

Because this stink bug initially feeds on common landscape ornamentals, homeowners are likely to be the first to spot new infestations. If you see an adult bug, collect a specimen, note the date and record the exact location (street address, town) and where the bug was, e.g., on the ceiling, feeding on vegetables, and, if possible, consult the Internet for ID verification purposes (Chris gets about 60% false positives). If it still appears to be a BMSB, contact Maier at Chris.Maier@ct.gov and he will ask you to send it to him at the Connecticut Agricultural Experiment Station, P.O. Box 1106, New Haven, CT 06504

Asian Longhorned Bettle -- Anoplophora glabripennis
Photo / Michael Bohne, Bugwood.org

Asian Longhorned Beetle (ALB)
Anoplophora glabripennis is an invasive insect that feeds on certain species of hardwood trees, eventually killing them. It most likely came to the U.S. inside wood packing material from Asia. Since first discovered in Brooklyn, N.Y. in 1996, it has caused tens of thousands of trees to be destroyed in Ill., Mass., N.J. and N.Y.

If it were to become established here, it could become one of the most destructive and costly pests ever to enter the U.S. If we don't find and stop the ALB, we'll lose more than trees. We'll lose industries worth billions of dollars -- and wildlife habitats, too. Our yards and neighborhoods will take decades to recover. ALB targets our favorite deciduous hardwood trees, including ash, birch, elm, European mountain ash, hackberry, horsechestnut, London planetree, maple, mimosa, poplar, willow and katsura.

Life Cycle & ID
Look for an insect 1 to 1.5 inches long with long antennae banded in black and white that are longer than the body. The body is shiny and jet black with distinctive white spots; and the feet on the six legs may have a bluish-white cast. Adult females chew a depression into the bark and lay a single egg beneath it. Egg sites are visible on the bark of the tree, and can be oval or round or small slits depending on the tree species and thickness of the bark. With a lifespan of 14-66 days, a female ALB can lay 30-60 eggs in her lifetime. The ALB spends most of its life as a larva inside a hardwood tree. The larva emerges from the egg and feeds on tree tissue just under the bark, then moves deeper and feeds on the woody tissue. This feeding and burrowing causes the tree to weaken and eventually die.

The larva becomes a pupa inside the tree. A year after an egg is laid, the adult beetle breaks its pupal casing and chews its way out of the tree, creating perfectly round exit holes about 0.375 inch in diameter. Adults emerge in July and August. They feed on leaves and small twigs and then mate, continuing the life cycle with the female beetles laying more eggs in the tree. Female beetles tend to lay eggs on the same tree every year until the tree dies.

Spot the Beetle. Stop the Beetle.
One of the most important ways you can help stop the ALB is to look for it and report it. Adult beetles are most active during the summer and early fall. They can be seen on trees, branches, walls, outdoor furniture, cars, and sidewalks. While it may appear threatening, it is harmless to humans and pets.

Signs of Infestation
Signs include shallow divots in bark where the eggs are laid, sap seeping from wounds in the tree, dime-sized (0.25 inch or larger), perfectly round exit holes in the tree, and sawdust-like material, called frass, on the ground and the branches.

Call to Action
Know all of the signs. Look for the beetle. Report it.

Due to the huge threat this beetle poses to America's trees, federal, state and local governments are taking steps to eradicate it, including quarantining infested areas. Local Beetle Busters are critical to USDA's mission to stop ALB. In fact, alert community members have been the first to report every ALB infestation that has happened in the U.S. so far. Use the tools provided at www.beetlebusters.info to learn the signs. If you think you've found an ALB or signs of infestation, always record the area where it was found. If possible, capture the insects you think are ALB, place them in a jar and freeze them -- this preserves them for easy identification. Take digital pictures of the insect and damage to your trees in case officials request them. Most importantly, be sure to report your findings online at www.beetlebusters.info or by calling 1-866-702-9938.

Emerald Ash Borer -- Agrilus planipennis
Photo / David Cappaert, Michigan State University, Bugwood.org

Emerald Ash Borer (EAB)
Agrilus planipennis is another Asian invader. EAB has killed tens of millions of ash trees, destroying forests and neighborhood trees.

Life Cycle & ID
Beetles are bright, metallic green about 0.5 inches long, with a flattened back, and purple abdominal segments beneath the wing covers. Adult beetles are most active during the summer and early fall. During the late summer, fall and winter months, larvae tunnel deep into the trees they infest. While EAB larvae are usually hidden from sight under the bark, they are creamy white and legless, with flattened, bell-shaped body segments and a pair of small appendages near the end of the body.

Host, Damage & Signs of Infestation
The adult beetles nibble on ash foliage but cause little damage. The larvae feed on the inner bark of ash trees, disrupting the tree's ability to transport water and nutrients. Canopy dieback begins at the top of a tree and progresses throughout the year until the tree is bare. Epicormic shoots (sprouts) grow from tree roots and trunk. Vertical bark splits may expose S-shaped galleries revealing the back and forth feeding pattern of EAB larvae. Adult beetles emerge from a D-shaped exit hole. There's increased woodpecker activity and damage as they forage for EAB, creating large holes when extracting larvae.

Call to Action
If you see the beetle or any signs of infestation, you need to report it immediately Learn to identify ash trees, and locate them on or near your property. Examine each tree for signs of infestation. If you observe beetles or evidence of EAB infestation, call 1-866-322-4512. If possible, take digital pictures of the insect and damage to trees. Go to www.stopthebeetle.info for guidelines and excellent information.

RESOURCES
• Connecticut Agricultural Experiment Station, www.ct.gov/caes
• UConn Home & Garden Education Center, www.ladybug.uconn.edu
• UMass Extension, http://extension.umass.edu
• Asian Longhorned Beetle, www.beetlebusters.info
• Emerald Ash Borer, www.stopthebeetle.info & www.emeraldashborer.info