Re: tent caterpillars

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On 30/4/2003, wrote:

>Tent caterpillars are proliferating

Funny thing about that, I was just noticing over the weekend that we
may be in for a bumper year either this year, or more likely it's the
start of a build up for the next couple of years.  My little apple tree
usually gets one or two nests--this year it's got 9, and the bitter
cherry has at least 3 or 4, when it's never had any (well, not in its 5
or 6 years of life).  None on the hawthorns yet, but it's early days.

In town, we get the western tent caterpillar, Malacosoma californicum
pluviale Dyar.  Orange and black.  If you get bluish ones, it will be
the forest tent caterpillar, Malacosoma disstria Hubner

>I know when I was a kid in Michigan tent caterpillars were very common (at
>least in some years)

They cycle here, too.  I've heard that it's supposed to be a 7-10 year
cycle, but I haven't seen a real peak since the early 80s, when they
were absolutely everywhere.  Couldn't even walk down the sidewalk
without squishing them when they hit the crawling stage.  And out in
the woods of Bothel, they were even more dense.  Truly impressive, kind
of like "The Birds" with a creepy crawly villain :-)).  The year after
that they were noticeable but not exciting, and the year after that,
almost a total population crash.  Since then, I always find 'em here
and there, but not worth mentioning.

>I'm wondering what course of
>action, if any, people suggest taking with them.

Break open the webs to make it easier for predators to get them.  (The
adult moths are apparently more edible though.)  Clip off the twigs
with the nests.  Some people use torches to burn them out, but that's a
little dicey.  Or, if it's a mature healthy tree, ignore them, because
'most any healthy tree can stand to be defoliated from time to time.
Pesticides are counterproductive, because the primary control is a
tachinid fly, which unfortunately many people think is a house fly and
so kill them too.  So if you see more than normal flies that don't
quite look like house flies, thank 'em kindly and send them on their

It's irritating , but I haven't found the species name, or even the
genus, for 'our' tachinid.  All of the general articles just say
tachinid (but there are 1300 species in NA, all parasitoids) and the
more tachinid specific sites talk lots about species, but not in
conjunction with our tent caterpillars.  Ah well, maybe a better google
search will turn up something.

Meanwhile, there are lots of images at google, and a good general tent
caterpillar site <>
which is especially to be commended for this paragraph:

"Benefits of a caterpillar outbreak can be numerous in a natural
setting. While caterpillars are distasteful to most birds, some birds
feed on them. When alders and other trees are defoliated, the shrubs
and trees below receive increased sunlight, giving some of them a boost
in growth. The eaten leaves pass through the caterpillar's body and
emerge as little pellets which can break down easily, returning
nutrients to the forest floor. Pupae provide nutritious meals for small
mammals, and moths are eaten by birds and bats."
Allyn Weaks   Seattle, WA  Sunset zone 5
Pacific NW Native Wildlife Gardening:
"The benefit of even limited monopolies is too doubtful, to be opposed
to that of their general suppression."  Thomas Jefferson

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