WHAT CAN WE LEARN FROM CICADA KILLERS?

by Whit Gibbons

July 19, 2015

We watched from our back porch as a killer ascended to the top of a 20-foot tree, carrying its defenseless victim. We knew what the outcome would be. The target of the earlier attack would be buried alive in our backyard or our neighbor's, while the perp left the scene unscathed, never to be brought to justice. We could have stopped the flagrant act that was clearly going to end unhappily for the victim, but no one wanted to intervene and interrupt such a fascinating natural phenomenon.

We were watching a female cicada killer, one of the giant black-and-yellow solitary wasps native to the United States, that had stung and paralyzed a large cicada. Cicada killers do not live in nests like some wasps, but instead each female digs a catacomb-like burrow underground, ready for development of her young from egg to larva to cocoon-building pupa to emerging adult. The process involves a female, which can be more than one and a half inches long, finding a full-grown cicada (which may be almost as big as she is), giving it a paralyzing sting, and then carrying it to the burrow. They really should be called cicada paralyzers.

The cicada ultimately gets carried to the prepared tunnel and deposited in a side pocket the cicada killer has dug, a sort of cave. The mother then deposits an egg on the permanently helpless cicada. Through a scenario reminiscent of the movie Alien, when the egg hatches, the larva enters the still-living cicada's body, and then proceeds to get the nourishment it needs to complete the development process. Skip the sugar-coated explanation: the larva literally eats the cicada alive over a several day period. After fattening up, the larva then turns into a fat pupa that spins a cocoon and stays underground in its own little crypt for a year or so. It emerges in the summer ready to go on a cicada quest if it's a female, or to look for female cicada killers if it's a male. As is true of many animal species, the males emerge from the ground and become active earlier in the summer than females.

But before all this teenage cicada killer development can happen, the soon-to-be mother faces the dilemma of finding a cicada. Step one is finding her prey during the daytime, but when she does, she is an awesome airborne attacker, being able to catch a cicada and bring it into submission with a sting in mid-flight. Considering what it's like and how painful it is when a honeybee or wasp stings creatures like ourselves that are a thousand times larger, what is it like to be a defenseless cicada? Would it be like our being jabbed with an 8-foot long, two-inch diameter needle with an oil-drum full of venom? Instant paralysis is a plausible result.

The cicada killer's next problem is getting the cicada to the burrow, which after the female's search may be a football field length away. Dragging it over the ground is one approach. One approach is for the female to use her back legs to hold the immobile cicada under her own body while using her other four legs to walk. But when the burrow is a long distance away, these enterprising insects have another strategy. Climb a tree with the cicada quarry in tow, and then launch and glide in the direction of the waiting cicada killer nursery. This is what the one we watched was doing as it walked rapidly up the tree trunk to get a higher vantage point and glide toward the burrow.

Meanwhile, what do the males do while all of this cicada killing is going on? They, too, have interesting behaviors to observe and probably one you are more likely to see. Next week's column will explain why male cicada killers will even attack humans, who really do not have to worry because the males do not have stingers.

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