Mournful Duskywing (Erynnis tristis) life history
Mournful Duskywing (Erynnis tristis) Life History

Egg (not viable)

First instar

Second instar

Third instar

Fourth instar

Fifth instar
Pupa, pupa

Fresh adult Mournful Duskywing, dorsal view, 11-26-20

Fresh adult Mournful Duskywing, ventral view, 11-26-20

I noticed several skipper eggs, some empty, on fresh leaves of a potted oak in mid-October of 2020. The timing was providential: after a few moments of inspection, what was obviously a recently-emerged caterpillar crawled into view. Eventually a total of 3 caterpillars were found. The unhatched eggs never eclosed; they appeared to have been predated or damaged in some way. I moved the plant indoors, sleeved the caterpillars, and the study began.

The caterpillars soon cut leaf shelters, as can be seen in the picture of the first instar. As they grew larger, they folded leaves together for their shelters.  Their development was slow but steady and by mid-November they were prepupal. I removed the leaf shelters from the tree and placed them in a holding cage so that I could put the tree outside.

I misted the leaves and each of the three caterpillars pupated at its own time. It is not uncommon, in my experience, for this to happen as winter approaches.  

Face of Mournful Duskywing

Two types of oak-feeding Duskywings are found in our area. I was not certain which species I was raising until the first adult emerged on November 24. It was quite unwilling to pose for photographs, even after release, so the second adult is the one figured to the right.

Mournful Duskywing Page