Winter Evidence of Insect Pests

Photo and article by Pamm Cooper for UConn Extension

The past year was interesting weather-wise- cool and very wet in June and then jumping  immediately to hot and dry for a couple of weeks. Lawns took a big hit from that combination, as did some root vegetables and shrubs. But certain insects had a field day out there and wreaked havoc on many shrubs, and if you missed them last year, 2014 may be a banner year for some pests if the cold doesn’t take them out.

One insect that occurred in large numbers is the bagworm  Thyridopteryx ephemeraeformis (Haworth), a moth whose caterpillar feeds mainly on arborvitae, juniper, pine and other evergreens . The caterpillars hide by day in a hanging bag made from silk and pieces of foliage. The female moths have no wings, eyes, mouth or legs and remain inside their bag where eggs inside their abdomen remain for the winter. Eggs begin to hatch in May through June and the hundreds of caterpillars begin feeding and constructing their own nests. Spread of the moths is slow because the females cannot fly, but stands of trees can be decimated over time. Look for the gray bags hanging from the affected trees during the winter and remove them, if possible.

Another insect pest that seems to be overwintering well this year are the boxwood leafminers, a pest of common boxwoods (Buxus sempervirens). Adults are tiny flies that may go unnoticed in the spring. The larvae are small yellowish maggots that feed within the leaves of newer foliage. Each leaf miner larva feeds within its own small area of the leaf causing leaves to look blotchy- yellowing and puffy- and whole leaves can appear like off- color pillows if several larvae are inside the same leaf. Heavy infestations can cause leaf drop, slow growth, or dying terminals. The larva overwinter within the leaves. Cut off infested stems in the spring before emergence of adults.

Alas, there are insect pests that favor our little New England homes for the winter. Some are simply pests because they are in our homes- like leaf-footed bugs and convergent lady beetles. But some are more than unwanted house guests. The brown marmorated stink bug Halyomorpha halys , first collected in Pennsylvania in 1998 but now present in Connecticut. It feeds on an assortment of plants, especially on fruits and vegetables. These bugs have white bands on their antennae- a diagnostic aid in identifying this stink bug from similar species. If you notice these bugs entering your home in the fall, it is best to kill them with the bottom of your shoe rather than putting them outside again. Better dead than alive to wreak havoc the next year in gardens and orchards…

So keep your eyes skinned as you are out and about. There are abundant bagworm cases out there- the Buckland Mall in Manchester near the Red Robin restaurant has a good section of Arborvitae hedge with them. And Manchester Community College has many arborvitaes looking the worse for wear.