Found a Mourning Cloak Egg Cluster

Today we found a cluster of mourning cloak (Nymphalis antiopa) eggs laid on an isolated willow tree (Salix) along the Ohlone Greenway Trail (Berkeley, California).

---

Considering that we basically never see the adult of the mourning cloak (Nymphalis antiopa) in all our years, it was quite a surprise that of all things, it is their eggs that we found on an isolated willow tree (Salix) growing at the end of the block of the Ohlone Greenway Trail in Berkeley California. To this day, more or less our only accounts of the butterfly have occurred at Albany Hill and they were all very old and worn males. Because these nymphalids have such a long lifespan, we sort of assumed that the very few we actually saw around were strays that may have occasionally breed on the willow trees but didn't have a strongly established population in our area. In fact, we still don't know even after finding the egg cluster. 

The egg cluster we found was located a few feet off the ground, about halfway up a medium sized willow (a variety that we have never encountered before and may or may not be native) that, strangely, was located in shade underneath BART tracks. The tree itself, however, was quite excellent. Also a bit odd was that the eggs were laid on the underside of a leaf rather than around a stem, which is a much more frequently reported laying site of antiopa. 

By the time we had found the eggs, it was quite clear that they were already close to hatching. The eggs were mostly all a dark shade of red; they are supposedly a pale yellow when first laid based on internet pictures. For some reason though, they didn't seem uniform in their stage of development with a few strips along the edges still looking orange rather than red and one of the eggs was empty. Either something ate it or the butterfly somehow laid this by itself. In any case, we hope that the eggs are not parasitized since this kind of thing tends to happen in the eggs of Nymphalidae. 

---

Authors
Brian Liang

---