Is it Bagworms or Fall Webworms Damaging My Trees?

   BAGWORMS

As Chris Penrose mentioned in a post last month, damage from bagworms is often seen this time of year by homeowners. Bagworms are the insects which make the pine-cone like structures at the ends of branches on many evergreen and other tree/shrub species in the landscape.  As the larva feeds and grows, often unnoticed throughout the summer, it enlarges the bag and begins to incorporate bits and pieces of plant material. By mid-August, the larvae are mature and they often move to a sturdy branch or other structure where they attach the bag firmly with a strong band of silk. We are now to the point where spraying insecticide on your tree or shrub at this time of year will not kill the larva inside the bag. Hand picking the bag at this time of year is the best strategy. The mature larvae usually attach their bags to a branch by wrapping extra silk, which does not decay rapidly. This band of silk may girdle the branch as it grows, resulting in dead branches several years later. Be sure to cut or scratch off this silk band when removing bags from a plant. FOR MORE DETAILS: http://ohioline.osu.edu/hyg-fact/2000/pdf/2149.pdf

Bagworms

Fall Webworm

Another pest often noticed this time of year is the fall webworm. It is actually the second generation of nests that are being seen now. The first generation nests (usually in June-July) are seldom as numerous or as large in size as those produced by the second generation. First generation nests normally involve only a few leaves.  Female moths however, 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 in Ohio typically reach their maximum size in the fall (late August thru October) which accounts for the common name. The fall webworm is not usually a serious pest in woodland forest stands, but infestations are of greatest concern to homeowners on shade, ornamental, and landscape trees. Here, loss of foliage and unsightly webs seriously reduce the aesthetics of the trees in the yard. In this circumstance, control of the fall webworm may be desirable. Control measures should be initiated when the webs and the larvae are small. Large webs make it difficult for insecticides to penetrate and contact the larvae within. Smaller larvae are also easier to kill. For effective control spray the web and the foliage surrounding the web. Many insecticides (such as (Sevin), orthene, BT or Malathion, etc.) may be used. Hand eradication is also possible when smaller webs are spotted early. Note…burning webs out of your trees with fire usually does more damage to the tree than the damage caused by the webworm. FOR MORE DETAILS: http://bygl.osu.edu/content/fall-webworm-update-0

Fallwebworm

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