Gypsy moths

Phil Graham Phil_Graham at
Fri Jun 9 19:44:14 EST 1995

In article <"95-06-09-17:36:29.20*LWE"@NCCIBM1.BITNET> LWE%NCCIBM1.BITNET at VTBIT.CC.VT.EDU ("larisa williams") writes:
>From: LWE%NCCIBM1.BITNET at VTBIT.CC.VT.EDU ("larisa williams")
>Subject: Gypsy moths
>Date: 9 Jun 1995 14:38:43 -0700

>It's that time of the year again, and this time they've reached us.
>I just noticed that my three-year old weeping willow was infested with
>gypsy moth caterpillars (I live on Long Island, NY).  They've begun
>defoliating the tree, and many of the branches are dying.  How can I
>treat the tree to eradicate these pests, and will my tree be able to
>recover?  Also, what other types of trees are their "favorite" meals?
>Thanks in advance for all your HELP!

Best bet is biological pesticide containing BT (Bacillus thurengensis or 
something close to that).  Dipel comes to mind as a commercially available 
formula.  This is a bacterium that affects the gut of caterpillars, so it 
doesn't harm beneficial insects or critters that feed on the caterpillar 
corpses.  If this is the first defoliation, your willow should recover fine, 
and even put out a new crop of leaves this year.  Repeated defoliation can be 
a problem, but one year or a couple of years in a row generally doesn't do 
lasting damage.  Gypsy moths are not very fussy, and eat almost all deciduous 
species, oak being a major favourite.  You would have to check on this, but I 
seem to remember ash as being fairly resistant.

Phil, Certified Arborist

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