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ENTM News : Cicada Killers Earn their Name

Cicada Killers Earn their Name
​Tom TurpinFrom "On Six Legs"July 11, 2013

One of the  largest wasps found in North America is called the cicada killer. These wasps range from 1 to 1.5 inches in length. Cicada killers are rusty-brown or black in color and have yellow bands on their abdomen.  


Because of their size and reputation as stinging insects, cicada killers can strike fear in the hearts of people who see them. But it is an unfounded fear. Cicada killers are really the gentle giants of the wasp world. 


There are at least two reasons for declaration. First, half of the cicada killers don't even possess stingers. They are males. Only female wasps have stingers - structures that are modified egg-laying devices. In general, it is the male cicada killers that people see zooming around as if defending their territory from other males. The second reason is female cicada killers go about their business of catching cicadas and ignore humans in the area. In addition, females do not defend their nests. About the only way to get stung by a cicada killer would be to catch her and then squeeze her in your hand, or accidentally step on her with a bare foot!  


Scientists describe eating habits of animals in terms of food specificity. In general, food consumed could be classified broadly as plant, animal or both. The human animal consumes both plant and animal food. However, some people narrow their diet and eat only plant matter. We call those folks vegetarians.  


Like humans, some insects will feed on both plant and animal matter. Cockroaches are a good example. Most insects, though, are specific to either plant or animal food. Within those general categories, insects can have either a broad or a narrow food range. 


For instance, caterpillars of many butterflies and moths will feed on the foliage of plants. That is the case with the largest giant-silkworm moth in this country, the cecropia. Cecropia caterpillars will feed on leaves from any number of hardwood trees. On the other hand, monarch butterfly larvae will feed only on leaves from plants in the milkweed family. 


Cicada killers are described as provisioning wasps. Provisioning wasps are specific about the food stored in the nest. Depending on the species of wasp, the food could be spiders, leafhoppers, aphids, caterpillars or cicadas. The young feed on the food - the provisions - provided by their mother. Such wasps either construct their nests of mud or excavate holes in soil, wood or plant pith.  


Cicada killer wasps dig holes in the soil as a nest sites. These insects prefer well-drained soil in a sunny location. As you might guess, nests are located near trees that will harbor cicadas. Homeowners note favorite nesting sites are along sidewalks or in flowerbeds, where plant density is low. 


The cicada burrow consists of a hole that can be as much as 70 inches long and a foot or more below the soil surface. That means that a lot of soil - as much as 100 cubic inches - will be brought to the surface when a burrow is constructed. A burrow can contain as many as 15 individual rearing chambers. Each chamber will be provisioned with one to three cicadas that have been paralyzed by the sting of the wasp. The paralyzed cicadas are the food source for the wasp larvae. The baby wasp will stop feeding and spin a cocoon prior to winter. It will conclude development and emerge as an adult the following summer. 


A true miracle of nature is watching a cicada killer capture and take her prey to the nesting burrow. Once the captured cicada is stung, it responds by emitting a high-pitched squeal. Some entomologists have dubbed the sound, "the scream of the cicada." The cicada scream quickly subsides, and the cicada killer grasps the prey in her legs and takes flight toward the burrow. The wasp is carrying a weight equal to or greater than her own. To get airborne she must launch from a tree limb, sort of like a fighter plane roaring off of an aircraft carrier.


A friend and I were engaged in a noontime jog last week when we saw the first cicada killer of the year. I explained it was a male cicada killer, based on it being smaller than the female of the species and because males emerge first each season. My friend asked how a cicada killer finds the cicadas to kill. I'm not sure, but I told him, "If I were you, I wouldn't make a sound like a cicada in the vicinity of cicada killers!"