Tuesday, October 26, 2010



They hatched! It's been 9 days since they were laid next to our front door. See my October 17, 2010 blog entry of their beautiful mother. Yesterday I noticed most of the grey eggs had turned a bright steel-blue color. I should have known some action was about to start, and yet I was a bit unprepared this morning as I was heading out the door.

I quickly got a container out. It's a simple plastic jar with cut pantyhose secured over the top with 2 rubber bands and tied in a loose knot. I've found rubber bands tend to deteriorate after a while, so using a backup is an easy solution. For insects that are tiny, like these 2mm Arachnis picta caterpillars, nylon keeps the critters from escaping and is stretchy enough to allow you to get into the container for feeding and cleaning.

I used a small soft paintbrush to collect the caterpillars onto a sheet of paper and then poured them into the container. In my haste, I neglected to add a damp paper towel to the bottom of the container. Some moisture is good, but when caterpillars are this small they can easily drown in a drop of water. Didn't you know? Caterpillars are not good swimmers.

I quickly threw in some organic carrot tops that I had on hand thinking primarily about accessibility to more of the same. Doh! I've inadvertently killed previous lepidopteran broods, because Btk is a commonly used organic pesticide. Later when I got back home, I went around outside and clipped various foliage with hopes they'd like one of them. I did a fairly extensive online search to see what the painted tiger moth larvae eat. There's no consistent information. Some say Lupinus, others say mustards or dandelion or bull thistle, and still others say radishes and Acanthus. I don't have easy access to any of those and am still kicking myself for pulling the dandelion shoots from my compost several weeks back.

ps 10/27/10 - I checked around noon and the caterpillars seem to like the carrot, dandelion, and fennel. They're already pooping tiny black specs, so that's a good sign. I'm still not sure if I'll keep these caterpillars, since it may take a whole year to properly rear them. Oh! I used the second pic of the container above, because the shiny plastic isn't very good with flashes indoors and I also wanted to show the unusually humongous waves we had yesterday.

pss 11/01/10 - Yesterday morning, several caterpillars had spun tiny little silk mats on the container. Today, I noticed several are bigger (3.5mm), lighter in color (must have molted over night), and hairier with bits of fluff next to them (cast exoskeletons). I'm still contemplating releasing them.

pss 11/06/10 - For the final post on these critters, click here.

7 comments:

texwisgirl said...

OMG! That's a wave behind that glass jar!? Eek! :)

Wow. They don't take long to hatch at all. Glad the little critters are eating what you supplied. But I'd understand if you just turned them loose to scrounge on their own too. Sounds like they may be a lot of work!

Nature ID (Katie) said...

twg, yep, the tide and wave heights were unusually big this week, post-full moon. They cleared the beaches of all the kelp that's been accumulating since late September, so, at the very least, it smells a bit fresher around here. Several local surfers have issued warnings on their forums to stay away. Unfortunately, on Tuesday we had another tourist die in Carmel after being swept away by a big wave. People don't seem to understand that our coast is not like the stereotypical Southern California beach of sun and easy surf.

And, I'm still debating whether I want to commit to a year of taking care of these caterpillars. I don't even have cats anymore... if that can tell you how nurturing I generally am.

Janet said...

caterpillermama!

John W. Wall said...

What a great pair of shots, to see the eggs and hatchlings. And so close to home!

Nature ID (Katie) said...

Ha! Thanks, Janet.

Yep, John, can't get too much closer to home than the front door.

Chris Grinter said...

Not sure if it will take a year, but a few months at least! BUT you can be lazy and feed them lettuce. Most tiger moths are like little pigs and will eat just about anything you throw in there - but sometimes it a lot easier just to buy some red-leaf and toss it in there.

If you do keep them, break them into smaller groups. Caterpillars that are reared in large groups tend to succumb to viral infections.

Nature ID (Katie) said...

Chris, from the little I could find online, it looks like there's only one generation of A. picta a year. They apparently go through a period of diapause in the caterpillar stage. I'm not sure if I have the patience to wait. I try not to feed Lepidoptera anything from the grocer, even if it's organic. Hmmm, maybe "organic" is the problem since Btk is so often used. I need to clean the container, but some are still going through their first molt and I don't want to disturb them.