Oso Flaco Flightless Moth

Scientific Name: Areniscythris brachypteris
Status: Species of concern (Category 2)

This remarkable moth (Lepidoptera: Scythrididae) is known only from the Santa Maria dune system along the coast of San Luis Obispo county (including the Oso Flaco Dunes, hence the common name.) What is remarkable about this moth is that it has adapted to its dune habitat by becoming flightless, in both sexes, a phenomenon unknown in any other continental Lepidoptera (though common to other insects.) This larva of this species was not discovered until 1968 at which time it was recognized as unusual. However, the adult was not found until 1972 by Dr. Jerry Powell after many years of concentrated suveys of dune Lepidoptera. The larvae are relatively indiscriminate in their feeding, having been successfully reared on numerous plant species (including Phacelia sp., Monardella sp., Lupinus sp., and many others) occurring in the dunes. The threats to this insect result from its very restricted distribution. It is known exclusively from this dune system. The primary reason for concern is the increasing use of the dunes in this area for intense recreational activity, namely off-road vehicle use. Long-term studies by Dr. Powell have documented the gradual (but unfortunately, not slow) destruction of this habitat over the past couple decades. That this moth was discovered so recently demonstrates how little we know, and moreover, how much we may never know, about such disappearing habitats.

For further reading:
Powell, J.A., 1976. A remarkable new genus of brachypterous moth from coastal sand dunes in California. Annals of the Entomological Society of America 69(2): 325-339.

Powell, J.A., 1981. Endangered habitats for insects: California coastal sand dunes. Atala 6(1-2): 41-55.