Pearl Crescent (Phyciodes tharos) life history
Pearl Crescent (Phyciodes tharos) Life History

Eggs two days after deposited, 11-29-11

Ready to eclose, 12-3-11

Recently-emerged and emerging caterpillars, 12-4-11





The face is very light-colored just after a molt, 12-29-11

A mature caterpillar, 1-4-12

About to pupate, 1-4-12

A fresh chrysalis, 1-6-12

Fresh adult Pearl Crescent, ventral, 1-19-12

Fresh adult Pearl Crescent, dorsal, 1-19-12

In October, 2011, I found two Pearl Crescent caterpillars on Wireweed (Symphyotrichum subulatum), a native aster. Having found (finally!) a local host for this common butterfly, I was anxious to raise some caterpillars from the egg. In late November we were enjoying pleasant weather, and I captured a female that was gravid. On November 27, she deposited 26 eggs on the host plant I provided her. 18 caterpillars were obtained, and all but one or two were raised to maturity.

The eggs a full week to eclose, because cooler weather had set in. The cold snap brought another problem: when I went to gather fresh leaves, my supposedly ample food supply disappeared overnight. There may have been a light frost, or the annual Wireweed may have just been at the end of its growing season, but it was clear that I needed a new source of food for the caterpillars. I began calling local nurseries; one did have some dwarf asters. These were obtained, but they were not in good shape and the caterpillars were did not appear to like their taste. In desperation I called Mike Rickard, who lives 60 miles southeast of my location, to see if he could suggest any alternative food sources. He said he would look around. The next day he let me know that he had not only located Wireweed, but he had gathered a good amount of it. Thanks to his generous help, I now had sufficient food for my caterpillars.

As can be seen in several of the pictures, the caterpillars generally did not eat the entire leaf. Rather, they scraped the surface, leaving behind a skeletonized leaf. This is typical of very young caterpillars of many species, but on this occasion even the older caterpillars followed this habit. Furthermore, they ate the outside layer of the stems in the same way (see, for example, the photos from 12/23 and 1/4). After noticing that they were using the stems, I offered them Spiny Aster (Chloracantha spinosa). I wondered if they might also use this leafless aster. However, they did not appear to accept it.

I normally raise caterpillars in an unheated room. In cooler weather, which we were experiencing, caterpillars develop rather slowly. The food was refrigerated, but it would not keep indefinitely. I decided to incubate these rather than risk the food supply. After the first week or so, they were kept at 80-85 degrees Fahrenheit. At this temperature range, development was steady, although still slower than I expected. The first caterpillar pupated on January 5, 32 days after it emerged from the egg. The rest pupated over a period of three-to-four days.

Face of Pearl Crescent

The pupae were not heated. I rather expected the caterpillars to remain in-chrysalis all winter, but this did not happen. Perhaps because January was abnormally warm, they began emerging on the 19th, two weeks after pupating. After 3-4 days, all had emerged and been released.

A comparison of several crescent caterpillars may be seen here.

Pearl Crescent Page