Wednesday, May 1, 2013

Six-spotted Tiger Beetle



On a botanical survey Sunday, we encountered scattered iridescent green beetles in multiple locations, perched on gravel like little half-inch long jewels.  Unlike most beetles, as we got within 3 feet of them, they darted away in a low erratic flight, landing on another nearby rock.  If you were colored this brightly, you too would take evasive measures to avoid being eaten.  Our bug man Bruce Bradshaw even captured one in a net which promptly escaped when I tried to transfer it to a container.

I assumed that they were tiger beetles although I couldn't get close enough to identify them.  Thanks to the miraculous performance of modern pocket cameras with 12X zoom, I was able to photograph it.  When we returned home and cropped several pictures, they confirmed that these were six-spotted tiger beetles, Cicindela sexguttata.

Tiger beetles earn their name from their speed as they run and pounce on prey.  All tiger beetles are capable of running fast in short spurts due to their disproportionately long legs.  Even their larvae attack ants and other arthropods with lightning speed as seen in this video of a British species.

Like the wolf in Goldilocks, they have large eyes and "teeth," the better to eat you with," especially if you happen to be a small arthropod.  The large eyes are a valuable asset if you are a predator.

The large white mandibles, give these beautiful insects a ferocious appearance.  Predominately daytime hunters, they can even capture their prey in flight.  Wikipedia reassures me that "Although they are strong enough to subdue their prey, they do not bite humans unless handled."  Good news, they don't hunt humans!
"My what big teeth you have"- normalbiology
Tiger beetles live independently except for mating.  Like some other beetles, the male stays mounted on the female for a while to discourage other potential mates.  Different tiger beetle species have very specific requirements for the soil the female tunnels into.
"The females lay eggs in sandy patches, and the larvae burrow into the ground when they hatch. Here they lie in wait until small arthropods walk by, where then the larvae pounce much like jack in the boxes. The beetles stay in larvae form for about one year before pupating. The beetle has a total lifespan of just under 5 years." Wikipedia
More pictures and information on prey and predators at fcps.edu.

4 comments:

  1. Tiger beetles are MOST cool. Thus far, the only species I've found here in Douglas County have been what seems to be several specimens of an intergrade between Cicindela purpurea purpurea x p. audubonii (no, I didn't make that taxonomic decision--it came from Ted MacRae [Beetles in the Bush blog]) and one specimen of Cicindela unipunctata. I highly recommend "A Field Guide to the Tiger Beetles of the United States and Canada" by Pearson, Knisley and Kazilek. I also bought Pearson & Vogler's "Tiger Beetles", but it has FAR more information than I need.

    ReplyDelete
  2. Another note: Most of my tigers were caught in dung beetle traps, and I found one on the front porch. They have a reputation for being very FAST!!!

    ReplyDelete
  3. Ron Huber publishes a small quarterly journal, Cicindela, to which I subscribe for ten bucks a year. Ronald L. Huber, 2521 Jones Place West, Bloomington, MN 55431.

    ReplyDelete
  4. Thanks, George, for the additional resources. There is also a website dedicated to Cicindels (tiger beetles for us plain folks) at http://cicindela.wordpress.com/

    ReplyDelete