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Walking along sidewalks in Evanston, a pedestrian may spot a U-shaped mound of dirt around a hole near a driveway or in flower beds, gardens or lawns: a burrow of the eastern cicada killer wasp.
The mound may be only an inch or so above the ground, but it can be 12-15 inches below the surface with tunnels that range from 30 to 70 inches long. These solitary wasps –they do not live in colonies as do other wasps – prefer to dig their burrows in well-drained, light-textured soil in full sunlight where there are cicadas in the deciduous trees nearby. The wasps are most active in July and August.
The eastern cicada killer wasp is 1 1/2 inches long. The abdomen is striped black and yellow, and the head and wings are rusty red in color. The female wasp locates a singing cicada and quickly paralyzes it by injecting venom into its abdomen with her large stinger. Once she has completed this task, she takes hold of the cicada upside down beneath her.
Then begins the long journey back to the burrow, as the wasp drags, flies or climbs until she can inter the living cicada in the depths of the burrow. She stores the hapless victim in a cell, laying her eggs beside the puncture wound from her sting. Then she seals the cell and continues hunting until she has filled all the cells in her burrow.
The puncture wound serves as an entry point for wasp larvae, which hatch within two or three days, to begin feeding. The tasty cicada “meal” lasts long enough for the larvae to grow into pupae. In about two weeks, when the wasp larva finishes eating the cicada, leaving just its outer shell, it will spin a cocoon and hibernate until the following spring.
The adults appear in the summer, feed, mate and produce new nesting burrows. The male wasps die after mating, and the females die after laying all of their eggs.
These eastern cicada killer wasps help to control the cicada population, which can harm new growth on trees.
The wasps are non-aggressive toward humans. According to the Stony Brook University (State University of New York), males cannot sting, and females can sting a person but rarely do so unless stepped on by accident or grabbed. Anyone allergic to bee stings should seek immediate medical assistance if stung.
Other sources include: Texas A & M AgriLife Extension. Animal Diversity Web: University of Michigan, Iowa State University, department of Entomology