Gray Hairstreak Butterfly

We found this funny-“faced” visitor in the garden this summer.  The Gray Hairstreak (or Common Hairstreak), Strymon melinus, is a common butterfly found in all 48 contiguous states.  It is often found in weedy and disturbed areas.  (I don't know what that says about my yard!) 

The Gray Hairstreak is one of the most “polyphagous” butterflies known, which means that it visits a wide variety of host plants.  The caterpillars have evolved to eat from more than 30 plant families. In central California, frequent hosts include ceanothus, mallows, legumes, clover, alfalfa, hollyhocks, and more.  I don't know if the butterfly was attracted to something specific in my yard or if it was just passing through, but it's possible that it found a few potentially appealing plants, including peas and cover crops of common buckwheat (Fagopyrum esculentum) and fava beans (Vicia faba). 

The butterfly is light gray with black and white lines across both wings.  The wings range from 1 to 1.25” tip to tip.  It is called a “hairstreak” because it has slim, hair-like “tails” on each lower hindwing.

That funny “face” is actually not a face at all.  Like many other butterflies, the Gray Hairstreak is designed to fool predators into mistaking its tail for its head.  When it is perched with its wings folded, the eyespots and “tails” look like a head. This may fool birds, lizards, and spiders into attacking the wrong end.  For the rest of us, it may simply be entertaining!

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