November, 2008

Aztec Spurthroat Grasshopper

The adult of the brightly colored immature locust pictured here has been described as "A plain-looking species" in Helfer's book, How to Know the Grasshoppers. However, anyone who has seen the gaudily colored little nymphs of the Aztec spurthroat grasshopper (Aidemona azteca), will agree that they are anything but plain. This species is very common in the Austin area, and most gardeners have noticed it, even if they didn't know just what it was.

The common name requires a bit of explanation. The Aztec part is obvious from the Latin species name, but there is another grasshopper found in Mexico that is called the Aztec grasshopper. That one, though, is in a different subfamily and the common appellation for this nymph's subfamily is "spurthroat," which refers to a unique knob present on the underside of the thorax.

The adults of this species really are plain looking. They are usually under an inch in length and range from dark brown to almost black in color; nothing like the brightly marked nymphs. Many people have never even noticed the adults and probably wouldn't recognize them as the same creature. The tinier the nymphs, the brighter their colors. As they molt and grow, their colors gradually fade a bit, until that final drastic change to adulthood. Since even the adults are small for grasshoppers, the nymphs are really tiny, hatching out at well under 1/4 inch in length, and retaining their bright colors only until they are about 1/2 inch long. Because of their small size, sometimes it is hard to tell that they are even grasshoppers, especially with the bright markings breaking up their outlines.