Orange Sulphur, Colias eurytheme, life history
Orange Sulphur (Colias eurytheme) Life History

Egg, 10-17-10

Freshening egg, 10-18-10

Young caterpillar, 10-20-10




Mature caterpillar, 11-2-10

Fresh chrysalis, 11-5-10

Pre-emergent chrysalis, 11-13-10

Fresh Orange Sulphur, ventral, 11-14-10

A flash of the dorsal shows she's a female, 11-14-10

Orange Sulphurs are fairly rare visitors to the yard, so when I saw one at ovipositing on Burclover (Medicago polymorpha) at the school where I work, I was quick to gather two eggs. Sure enough, now that I had eggs, shortly thereafter I observed two females ovipositing in the field behind my house. They were using seedlings of two plants. One was Bearded Dalea (Dalea pogonathera); the other I was not able to identify. It was amazing to see the butterflies both locate and lay eggs on such small plants. Presumably the seedlings would grow fast enough to feed the caterpillars, or they would be able to move to other plants when their food supply ran out.

Dalea, as opposed to Burclover, naturally occurs in this area, so for this essay I used the pictures of the caterpillars on Dalea. The caterpillars had dark bodies and heads when they emerged, but the bodies greened up quickly, and the head became green after what was probably the second instar.

The caterpillars took only 3 days to eclose from the eggs. One took 14 days to pupate and emerged nine days later. The journey from egg to adult therefore took about 28 days.

Orange Sulphur