Field Crescent (Phyciodes pulchella) is a small-medium butterfly, with a wingspan of 1 to 1.75 inches. It can be seen from April to October. Numbers peak in July. Host plants are various Asters.
This butterfly can be hard to distinguish from the Northern Checkerspot female, especially when the specimen is worn. Both pattern and size are similar.
Butterflies usually mate in a back-to-back position, joined together at the tip of the abdomen (see the Mylitta Crescent photographs for a rare exception). In some species, females mates only once, but for most species, they mate multiple times, albeit with a gap of several days in between. The reason has to do with how the male passes on his sperm. Sperm is not deposited directly. Instead, the male takes some time to form a spermatophore, which occurs inside the female. Some matings last only 20 minutes, others can last a whole day or more! A spermatophore consists of a tough outer envelope, an inner matrix of fluids, and a bolus of sperm. While the exact number varies across species, a male may pass on as much as 13% of his total body weight through the spermatophore during mating. It is large enough to block the female’s reproductive tract, so she can’t mate again for a few days till she has broken down the outer shell of the spermatophore and fertilized her eggs. Only then is she ready to mate again.
This may explain why, for many species, males are observed much more frequently than females. Males hang around in the open every day, searching for receptive females. For a few days after each mating, a female does not appear except to feed. And the average life of an adult butterfly is 3 weeks. “A few days after each mating” can add up to half its life.
It is found in the western third of the US, and in British Columbia and Alberta, stretching north through Yukon into Alaska.
