Red Admiral Eggs on Pellitory

Completely by accident, we found some pellitory (Parietaria) plants clobbered in red admiral (Vanessa atalanta) at Albany Hill (Albany, California).

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For the longest time, we have seen red admirals (Vanessa atalanta) flying at Albany Hill, or even in the city, during the summertime. Last year we discovered just a smidge of stinging nettle (Urtica) growing inside the path of Albany Hill, but never found any of their eggs. Obviously, these plants weren't enough to support an actual population. In fact, Albany Hill data from 1995-1999 concluded that Vanessa atalanta were most likely vagrant since no Urtica was recorded at the site during that time. The authors suspected urban pellitory (Parietaria) or baby's tears (Helxine or Soleirolia) as the more probable host plants. 

Today we happened to stumble across a plant growing along the fence outside of Albany Hill that was getting a lot of attention from a red admiral. We almost jumped when we saw that the tiny plant was utterly suffocated in fresh eggs. The plant, as it turned out, was in fact some variety of pellitory which belongs in the same family as the nettles. We found more of the stuff growing along the same fence, all covered in eggs or even first instar larvae. It was quite clear that the red admiral population was getting quite desperate and that they were basically dependent on these small plants, almost all of which looked so young that they could have only grown in this year. 

Interestingly, we also found a single west coast lady (Vanessa annabella) egg today on mallow (Malva), another exotic weed. Whereas the atalanta eggs seem to have about 8-12 ribs, the annabella have at least two to three times that.​

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Authors
Brian Liang

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