Beetles

07/07/11
Newsletter Topics

#1 - Tips of the Week

#3 - Misunderstood Plants

#5 - Popular Gardening Myths

#2 - Summer Bloomers that Wear Well

#4 - Universal Watering of your Landscape

#6 - Insect Updates

Fourlined Plant Bug

Taken from the B.Y.G.L. (Buckeye Yard and Garden Online) Newsletter
Contributing Authors: Pam Bennett, Joe Boggs, Cindy Meyer, Jim Chatfield, Erik Draper, Dave Dyke, Gary Gao,
David Goerig, Tim Malinich, Becky McCann, Bridget Meiring, Amy Stone and Curtis Young

Dave Goerig and Dave Shetlar reported that they are seeing heavy fourlined plant bug (Poecilocapsus lineatus) damage on annuals, herbaceous perennials, and some woody ornamentals in northeast and central Ohio, respectively. Dave Shetlar also noted that most of the bugs have now reached the adult stage in his part of the state. This sucking insect feeds on over 250 herbaceous plant species. The quick-moving nymphs are reddish-orange with black wing-pads. The appropriately named adults vary from yellow to green in color and have four black stripes down the wings.

Like many plant-feeding Hemipterans, the fourlined plant bug injects enzymes into the plant causing cells to collapse. The bugs then feed on the resulting "slurry." The damage appears as small, round, black sunken spots which may coalesce into extensive blackened areas on infested leaves. The symptoms are commonly mistaken for a plant leaf disease.

The plant bug has only one generation per year. However, both the adults and nymphs are heavy feeders and high populations can produce significant plant injury. Targeting the early instar nymphs for control reduces the overall damage caused by this insect, thus it is too late for control measures to prevent much of the damage that will occur for the season.

Fall Webworm

Dave Shetlar reported that first generation fall webworm (Hyphantria cunea) nests are becoming evident in central Ohio. Fall webworms only feed on leaves that are enveloped by their silk nest. As caterpillars grow in size, they expand their nest by casting silk over more leaves to accommodate their expanding appetites. First generation nests are seldom as numerous or as large in size as those produced by the second generation; the first generation nests normally involve only a few leaves. Female moths often lay their eggs on or near the nests from which they developed, thus second generation caterpillars expand the nests once occupied by first generation caterpillars. The second generation nests typically reach their maximum size in the fall which accounts for the common name.

There are two types of fall webworms, known as "races," and both races are found in Ohio. The two races differ in coloration, and to some extent, they also differ in host preferences, nesting behavior, and the timing for spring adult moth emergence. Caterpillars of both races are very hairy and they feed as skeletonizers on leaves enveloped by webbing. The caterpillars of both races may also be found on a wide variety of shade, ornamental, and fruit trees. Both races have two generations per year and they spend the winter as pupae in cocoons located in leaf debris or in the upper layer of the soil; however, moths emerge at slightly different times in the spring.

The so-called "black-headed race" webworm caterpillars have black head capsules and two rows of black bumps (tubercles) running the length of their yellowish-white bodies. Black-headed

caterpillars typically feed in a common web until they are half-grown, then they may separate to produce small, elongated, wispy nets along tree branches that envelope only a dozen or so leaves. Black-headed race moths usually emerge from overwintering cocoons in mid-to-late May in Ohio.

Red-headed race" webworm caterpillars have red to reddish-orange head capsules and two rows of reddish-orange tubercles running the length of their light to dark tan bodies. Adult moths usually emerge from overwintering cocoons 2-3 weeks after the black-headed race adults have emerged. Red-headed webworms remain together throughout their development to produce truly spectacular multilayered nests enveloping dozens of leaves at the ends of branches. Although first generation female moths of both races often lay their eggs on or near the nests from which they developed, this is behavior is most commonly practiced by the red-headed race which explains their often truly spectacular sized nests.

If first generation nests are few in number and easily accessible, the best control approach is to physically remove and destroy the nests and caterpillars. Insecticide applications should be used sparingly since insecticides may limit the impact of bio allies. There are over 50 species of parasitoids, and 36 species of predators known to make a living off of fall webworms. In past seasons, parasitoids have proven to be very effective in reducing year to year populations of this defoliator.