Wednesday, September 21, 2011

An Overview of Tiger Beetles

While you are out in open, sandy areas on nice sunny days take a good hard look at the ground. Oftentimes you can see a little metallic flash zing away from you, either running or flying. Chances are you just saw a Tiger Beetle - a not uncommon group of ground-beetles (Carabidae).

Cicindela purpurea, Nantucket 14-Sept-2011

These gorgeous little bugs are one of the major groups that has received state and federal protection via the endangered species act - eight of the nine "listed" beetles in Massachusetts are tiger beetles including the above species, the Purple Tiger Beetle. It is a rare and declining species in Massachusetts, many populations existed historically throughout the state, but very few are known now.
Notice the massive mandibles for catching prey on this C. repanda.

All tiger beetle species eat other invertebrates, often including ants, pillbugs and crickets. They run the prey down and grab it with their massive mandibles or scavenge dead or dying creatures.

Cicindela repanda, July, Nantucket
The life-history of these beetles is interesting. Certain species here live for two years; overwintering during the first year as a larva and the second as an adult, breeding in the spring of their second year. Others overwinter as larvae and emerge as adults in the summer then breed and die by fall. In one location you may find two species - often C. repanda and C. hirticollis - in the exact same areas, but almost never at the same time. Perhaps this is an adaptation to minimize competition, but no one has quite resolved that question yet.

C. hirticollis, an individual I collected as a larva and raised for several months
As insects go, these have proved quite easy to keep in captivity. The larvae can be fed small crickets or flour moths and the adults seem to enjoy crickets and pillbugs, though I also fed them dog food and they seemed to enjoy that as well. I have not tried overwintering any, as this process apparently is difficult.

Cicindela sexguttata, a common species that I cannot get to pose for a picture while alive.

Cicindela dorsalis dorsalis, collected in the 1920's by C.W. Johnson, now severely endangered

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