Friday, October 7, 2011

A Cold-Blooded Killer

(originally posted July 19, 2011)

That’s right; this week’s blog is about a cold-blooded killer. Although your mind may be conjuring up Hollywood-inspired images of murderous villains and monsters, this killer is neither of those. This is literally a cold-blooded killer; the eastern cicada killer. Since the cicada killer is a wasp that kills cicadas, and since all insects are ectotherms (i.e. cold blooded), the description is perfectly and geekily accurate! Getting up close and personal with a Hollywood killer may not be the best idea, but observing a cicada killer is not as crazy as it sounds.

Considering my previous blog on the carpenter bee, you might think I have a thing for large and intimidating insects, and you’d be absolutely right. These wasps are huge—the females reaching 2” in length—and their appearance is intimidating. But as with the carpenter bee, males lack the ability to sting and females do so only rarely, like when being handled or stepped upon. (For information on capturing giant wasps for “fun,” consult Mr. Nature Geek, though to his credit he has never been stung...yet.)

A day in the life of an eastern cicada killer is quite fascinating, especially when witnessing it firsthand. Female cicada killers are the ones that earn the wasp their namesake. After mating, a female will locate a cicada, subdue it with a paralyzing sting, and then carry it back to a burrow she has excavated in the ground. This is quite the feat considering the cicada can be twice her weight! Last summer, a female cicada killer attempting to fly with her prize tumbled to the ground at my feet. She then climbed my leg, cicada in tow, to gain some altitude so she could continue her flight. Even I will admit this act was somewhat unnerving!

Upon reaching her burrow, the female will create a chamber for each egg that she lays, each on its own cicada. Male cicada killer eggs (yes, the females know which of her eggs are male or female) are given one cicada upon which to feast upon hatching, and female eggs are supplied two or three cicadas due to their larger size. The emerging larva consume their cicada meal within a few days, and then prepare themselves to overwinter underground.

For the male cicada killers, most of their time involves searching for females and chasing off intruding males, which sometimes escalates to aerial combat that involves two or more males grappling midair. I once watched a patch of vegetation in the Hillsborough River State Park campground in Florida that was being patrolled by a male cicada killer. Perched high on a broad leaf, I could see him physically turn his body to survey his territory, sometimes leaving his post to investigate any passing flying object. Once the object was either determined to be non-threatening or another wasp that was then chased off, the male would return to his leaf, once again turning his body left and right.

Although cicada killers are by definition “cold-blooded killers,” they do not pose the same threat to humans as zombies or crazed people armed with chainsaws. This summer I challenge each one of you to get close to a cicada killer to watch it in its daily activities—just think of it as one of those double dares you’d always do as kids at sleepovers.

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