the woolly bear caterpillar

[Richard Worth]

Wolfish,
I am currently rearing wooly bears (Pyrrarctia isabella) on willow 
leaves here in western Oregon.
They seem to be relatively common here on the west side of the 
mountains and I have encountered them in the Columbia Gorge as far 
east as The Dalles.  I don't remember seeing them in California 
growing up in the Bay Area.  We did have salt marsh cat's, though. 
They move moderately fast (faster than most butterfly larvae but not 
at the twitchy, blinding speed of some leaf-rolling tortricids) in 
their own undulating way and one can often times see them crossing 
the road out in the country in late summer.  They seem to feed mostly 
at night.  During the day I have seen them around the base of plants 
but up on the leaves.

Actually, I have never reared them before until now.  I was hoping 
someone out there can tell me the best way to overwinter larvae. 
There has been a lot of talk on the list about getting pupae through 
the winter but not much about larvae.  For now, I keep giving them 
leaves and they keep eating.  Should I just keep giving them leaves 
as long as the leaves hold out (we are in the grips of fall now)?
Cheers and thanks,  Rich


>I took some time to look through my library last night for information on
>woolly bears.  Note that the moth is called Isabella Tiger Moth, and is
>listed as Pyrrharctia isabella (J.E. Sm.) in the Peterson Field Guide.  You
>may also find it listed as Isia isabella in other books.
>
>A good reference (should be in the public library) is Donald Stokes' book A
>Guide to Observing Insect Lives (1983, Little Brown & Co.).  It has good
>information for the general "layperson".  (The entire Stokes Guides series
>is fascinating reading - I highly recommend them.  They are not typical
>identification guides but rather give fascinating information once you know
>what you have).  One of your questions dealt with speed of woolly bears -
>the Stokes book lists the speed at 4 feet per minute ( .05 miles/hour )
>which is really moving for a caterpillar!
>
>You should also check out the Peterson Field Guide #30 Eastern Moths by
>Charles V. Covell, Jr. (1984, Houghton Mifflin Company).   This field guide
>mentions that the amount of black and red changes with the instar of the
>caterpillar - that is, with every molt, the caterpillar becomes less black
>and more red.  (Don't think that another great weather forecast tool may
>have just been shot down - see note below in the next book).  They
>over-winter as larva and pupate in the spring.  There are typically 2 broods
>per year.  It also says the moths are common in the region covered by the
>field guide which is North America from 100 degrees longitude east.  I have
>no idea of how common they may be in the West......
>
>If the library has a copy, Ninety-nine Gnats, Nits and Nibblers by May R.
>Berenbaum (1989, University of Illinois Press) has some interesting
>additional human interest tidbits such as Topsell in 1608, in his History of
>Serpents, compares the caterpillars to superstitious pilgrims in how they
>wander around and eat that which is not none of their own.  He already
>refers to them as Bear-worms.  The book also quotes a weather study by C.
>Howard Curan of the American Museum of Natural History in New York.  He
>compared the caterpillar forecasts to the official weather forecasts from
>1947 - 1951 and found the caterpillars to be more accurate!  The forecast is
>made based on the amount of red - the more red, the colder/longer the
>winter.
>
>I had other references but they did not have anything new to add to what is
>covered in these three books.
>
>Hope this helps!
>
>  > ----------
>  > From: 	wolfish at my-deja.com[SMTP:wolfish at my-deja.com]
>  > Reply To: 	wolfish at my-deja.com
>  > Sent: 	Wednesday, October 11, 2000 8:36 PM
>  > To: 	leps-l at lists.yale.edu
>  > Subject: 	the woolly bear caterpillar
>  >
>  > A friend of mine is a writer, and a chapter or two of a novel she's
>  > writing hinges on "woolly bear" caterpillars.
>  >
>  > She's had some difficulty finding extensive information on things like
>  > range, how quickly they move, etc. -- essentially, a day in the life of
>  > a woolly bear caterpillar. I challenged myself to find the information
>  > for her.
>  >
>  > Does anyone have a good source of detailed information for the
>  > layperson, on or offline? Or, better, would anyone be willing to share
>  > what they know?
>  >
>  > Thank you in advance,
>  > Wolfish
>  >
>  >
>  > Sent via Deja.com http://www.deja.com/
>  > Before you buy.
>  >

Richard A. Worth
Oregon Department of Agriculture
Plant Division
rworth at oda.state.or.us
(503) 986-6461
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