Western Tailed Blue butterflies and caterpillars

Earlier this month, I noticed lots of these cute little butterflies at the arboretum.


This is a Western Tailed Blue, Cupido amyntula. The picture above is a little blurry, but at least you can see the "tails" on the hind wings.


Many of them were paired up.


As I looked online to identify these butterflies, I read that their larval host plant is the rattlepod bush, also called loco weed. (Astragalus trichopodus) Of course, it just so happens that there were several patches of that very plant in the area where I found the butterflies. So of course, I had to go back and look for the caterpillars.


I figured that the caterpillars would be small and well-camouflaged. But I was still disappointed when I couldn't find any. Then I decided to take a closer look at the pods.


Some of them had holes in them. I opened a couple of the holey ones to find just an empty pod. No caterpillar, no seeds. So I sought out the younger looking, greener pods...


See that little shadow in there? It's a caterpillar.


I opened a pod with a bigger shadow. It had a larger (but still very small) caterpillar inside. He had clearly been eating the tiny bean-shaped seeds in there. You can see the empty stems left behind that had most likely each held a seed.


He didn't like that I had exposed him. I put him back on the plant, hoping he might chew his way into a new pod.