Life Cycle of the Cicada Killer

  The following is a multimedia natural history. Sound links are about 10 seconds long (44Kb) in .wav format, which is easily read by Windows. Click on any thumbnail to see a full-sized image. The contents of this page are intellectual property. Photos or text may not be used without prior consent. All material 1998-2014 Joe Coelho, except electron micrographs by Paula Edgar, and audio by Sharon DeWitt.

The beginning

Cicada killers are around at the time that coincides with the presence of their cicada prey, which are well known for the loud vibrating call of the male. Larvae of annual cicadas (not the 13- or 17-year species) emerge from the ground, climb a tree trunk, and  eclose from their pupal case to become adults. Click here to see a brief animation of a cicada emerging. Male cicada killers (Sphecius speciosus Drury) emerge from mid-July to the beginning of August, a couple of weeks before the females. They break out of their  pupal cases and dig their way out of burrows where they spent the winter, leaving telltale holes in the ground. Males stake out territories where females are likely to emerge, defending the airspace within their territories against conspecific males, and chasing anything that flies on the chance that it might be a virgin female. Males generally perch in a  typical posture on some object within the territory.

The mating

Soon after virgin females emerge, they mate, but only once. The male occupying the territory in which the female emerges is usually successful in mating her. They fall to the ground and couple. Other males may try to horn in, forming a  cluster around the mating pair. If disturbed, the pair may fly off and land elsewhere. Luckily, they can fly off whenever they feel like -- whereas we humans are dependent on international airlines, Fly and similar websites. Imagine how different things would be if we weren't so attached to terra firma. We would never stop traveling!

The digging

Females are equipped with a pair of shovel-like mandibles and stout legs. The burrow is begun by chewing a hole into the substrate, then kicking the dirt out with the legs while backing up. Females have a pair of large spurs on each hind limb that may assist in kicking dirt out of the hole. Burrows may extend several feet beneath the surface, and have many branches and cells for holding cicadas and larvae. In the end, a large  pile of soil (tumulus) accumulates next to a hole large enough for the average person to stick his/her thumb into. After completing the burrow, the female makes numerous circular flights of increasing diameter to  orient to the burrow entrance. If disturbed in their burrows, females, surprisingly, do not often fly out to sting the intruder. More often they remain in the burrow and produce a nasty alarm buzz, which is probably quite a deterrent. It has to be because, like most members of their family, cicada killers have extremely weak stings.

The hunting

Females are twice the size of males. The obvious advantage is that they can carry much more than a male could. A female flies out and inspects trees until she finds a cicada. After she stings it, the cicada becomes paralyzed within one minute. The wasp then grasps the base of the wing of the cicada with her middle legs, and flies with the cicada in an upside-down position back to her burrow. Females generally cannot lift a cicada upward in flight (although sometimes they can if they get a light one). Therefore, if the burrow is too far away, the wasp may have to carry the cicada up another tree on foot, then fly down toward the burrow. If the female lands some distance away, she may have to  bear the prey overland to reach it. The female  drags the prey down into the burrow. The cicada is secured in a pre-dug cell, and an egg is laid upon the cicada. The cell is provisioned with one cicada if the egg is male, two if it is female.

The winter

The cicada killer's venom preserves the cicada, which will live in a paralyzed state twice as long as an unstung, unfed cicada. This may sound like something an alien would do in a space game, but in fact this is just how the cicada killer's venom works. Within two weeks the larvae have eaten the paralyzed cicadas and grown into prepupae, the form in which they will spend the winter.

The end

Females live about 30 days. By mid-September they are hard to find.  This aged female was found in late September in Indianapolis, Indiana. The last of what had been an enormous nesting aggregation, she crawled about, unable to fly.

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