Seasonal Change:Fall Webworm Appears in North America,But Poses Little Risk

The early hours today were cool enough for a jacket,a foretaste of meteorological autumn,which begins on 1 September.Walking by a stand of mature timber this late July morning in Northern Maryland,I also noted one of the earliest indicia of seasonal change:fall webworm on the ends of a few branches.These silky webs are spun by larvae of the fall webworm moth (Hyphantria cunea) to protect themselves while they feed on the leaves of some 90 species of deciduous trees.The trees range from hickory and walnut to cherry and birch.In the event,they only rarely defoliate a tree,and even when they do,it usually isn't fatal.The worst thing about it is that the webs may be seen as unattractive.*
The webs can extend up to three feet at the ends of branches.In my experience,you  normally only see a few webs here and there on a given stand of timber-at least at this latitude.Should you wish to remove the webs,one way is to lop the affected branch tips off and crush the caterpillars.You can also tear a hole in the webs so predators such as birds and wasps can eat the caterpillars,or spray pesticides-but these are always best kept as a last resort.Most people in North America just tolerate them as a sign of approaching autumn.*
When they are full,the larvae pupate in a cocoon under leaf litter or in cracks and crevices in the soil,emerging as white moths-or white with black wing spots-late the following spring.The larvae themselves are greenish or yellowish with white hairs and black dots along their backs.*
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