I recently asked our arborist, John Salata about fall web worms, those yucky white webs one sees in tips of trees along roadsides this time of year. Here is his response, plus a link to a UMass web site about the problem.
Generally we don’t do much in the way of controlling fall webworm. Not to say that we wouldn’t in severe cases, but most years control consists of pruning out the more conspicuous infestations. Once the caterpillars have established their web nests (and often you’re not aware of them until they’ve done so), they’re very difficult to control chemically, so removing the affected branches or physically disrupting the webbing to expose the caterpillars to predators are the only control options I’m aware of. Fortunately the damage is largely aesthetic….although I have seen some trees (not here) suffering severe infestations over multiple years that may experience trouble down the road as a result. From what I’ve seen, fall webworm seems to be quite abundant this year….possibly why guides seem to be getting more questions about it.
http://www.umassgreeninfo.org/fact_sheets/defoliators/fall_webworm.html
