Infant caterpillar help needed

[Allyn Weaks]

A clutch of caterpillar eggs hatched out under my microscope last night,
and I'd like some help with ID and how to raise them.  I posted about the
eggs last night on s.b.e.misc because I didn't know if they were leps, but
know I at least know that much.  Quoted bits are from that other post.
 
> I'm in Seattle, WA.
 [snip]
> Eggs bright yellow,  about 3/4 mm in diameter, ovoid, and flat on the
> bottom where attached to the leaf.  About as tall as wide.  25 were laid,
> roughly in rows mostly three in a row, sometimes four.  A few are
> touching, but most are separated by about the radius of an egg.  The
> surface is shiny, with a few shiny warts of varied size, mostly low on the
> eggs.  There are also shallow grooves a bit like dry clay fractures, but
> not jagged.
 
[snip]
 
Timeline:
 
Sunday -found eggs on himalayan blackberry (Rubus discolor), brought them inside
Thursday 11pm - faces and hairs had developed, mandibles moving
Friday 2.30 am - first break in shell
3am - first hatchling out
5.10am - second one out (very slow, took 45 minutes once his head fit
through the hole)
5.30am - two more are out
7am - everyone out (20 out of 25 eggs, 5 never developed)
most of the 'pillars came out very quickly (a minute or two) once the
holes were big enough.  I dunno what #2's problem was.
 
There were three eggs that probably hadn't been fertilized, and two that
had been damaged.  A few of the 'pillars ate parts of them, and nibbled on
some of the empty shells, too.
 
The caterpillars:
 
~2.5 mm long, 1/4 mm wide.  Yellow, but paler than the fresh eggs. Long
(rough, about 1.5mm long) black hairs on back; come from large bumps
(warts? tubercles?)  From the 'spine' down on each segment, there are
three big bumps on each side, each with at least one black hair.  After 12
hours out of the eggs, the bumps are starting to darken into a sort-of
olive green, with a lighter ring where the hair comes out.  Then an almost
invisible spiricle, then more bumps with clear hairs (shorter than the
black ones), but I can't count completely or see well without killing
one.  There are a few shorter clear hairs on top--so hard to see I can't
get a good count of them.  Looks like they might come from teenier bumps
closer to the 'spine'.  The black hairs come singly from the bumps except
on the thoracic segments, topmost bumps, which have two each.  There's
some individual variation for whether a hair is black or clear, and one
has extra hairs on the 4th abdomenal segment, top bump.
 
Prolegs are nearly as long as the real (segmented) legs, ~1/4 mm
 
Head is shiny, with diffuse dark patches reminicent of large compound
eyes, then a break, then dark again at the ocelli.  4? ocelli each side
 
Mandible tips are red with 4 or maybe 5 teeth.  When the light hits them
just right, they are shiny ruby red, otherwise with a slight brown tinge
 
Haven't found a food preference yet.  They are just starting to move away
from the eggs (less dispersal than moving to the other side of the nearly
dried up blackberry leaf).  I forcibly removed one from the group earlier
and put it on a thimbleberry leaf (R. parviflorus, native here), near
small fragments of thimbleberry and blackberry (so edges would be
available to munch).  Seemed to like to crawl on the edges, showed no
preference for either species, and didn't eat either.  It's now sitting
still underneath the thimbleberry fragment (pining for his sibs?)  I'd
prefer to feed thimbleberry, since when I found the eggs, I'd already
chopped down all but a few leaves of the blackberry, and I can't count on
a pesticide-free source of it as fodder.
 
How long do caterpillars usually go before they start to eat?  How long
before they have to eat?  What else should I try giving them?  There are
darned few other plants near that blackberry bush, so if Mom thought the
kids could walk to a tastier plant, I suspect she'd been drinking the
wrong nectar :-).  For now I have them in a container with thimbleberry,
some blackberry, birch, and a weed or two.  I can add a few other mostly
pnw native tree and shrub leaves to the mix if need be.  But at least for
now, they seem more interested in lurking than hunting for dinner.
 
Many thanks for any help in getting them to adulthood!  (Or even the
second instar :-))
--
Allyn Weaks  allyn at teleport.com  Seattle WA, USDA zone 7/8
Pacific NW Native Plant Gardening: http://www.teleport.com/~allyn/natives/
My email address is in WA State.  If you don't want to pay me the
$500 I can legally collect, don't send me UCE/spam.