Cicada killers out and terrorizing residents
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EmailEditor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
I received several phone calls this week about gigantic wasps that folks were finding digging holes in their lawns. Terry McLean at the Genesee MSUE office sent me three specimens (see photo) that a local pest control guy thought might be some kind of exotic species. These spectacular insects are known commonly as “cicada killers” and scientifically as Sphecius speciosus (Hymenoptera: Sphecidae). They are the largest wasp that occurs in Michigan.
The cicada killer wasps attract attention due to their large size and the burrows they dig in home lawns. These insects occur in all states east of the Rocky Mountains and prefer to dig their burrows in sandy, bare, well-drained soil exposed to full sunlight. The wasps feed on flower nectar, while the immature or larval stages feed primarily upon cicadas that are brought into the burrow by the female wasp. Like other solitary wasps with no large colony to defend, cicada killers usually ignore people as they go about their business of digging holes and hunting for cicadas. Although pretty much docile, they can give a painful sting if bothered.
A mound of fine soil surrounds the burrow of each female cicada killer. Since colonies of burrows are common, infested lawns usually contain several mounds that can smother the grass. However, they prefer to nest in areas of sparse vegetation, and rarely infest thick, vigorous turf.
Cicada killers overwinter as larvae in the soil. Pupation occurs in the spring and the adult emerges in mid-June to early July. Emergence continues throughout the summer. Females feed, mate and dig burrows for several weeks before preying on cicadas. Excess soil thrown out of the burrow forms a regular, U-shaped mound at the entrance.
The females search tree trunks and lower limbs for cicadas. The wasp stings its prey, turns the victim on its back, straddles it and drags it or glides with it to the burrow. Each burrow includes several cells where larvae are raised. Each cell is furnished with at least one cicada (sometimes two or three) and a single egg before being sealed off. Two to three days later the egg hatches. Depending on the number of cicadas in its cell, the larva feeds for 4 to 10 days until only the cicada's outer shell remains. During the fall, the larva spins a silken case, shrinks, and prepares to overwinter. Only one generation occurs each year.
Cultural practices can prevent or eliminate the establishment of cicada killer colonies. Adequate lime and fertilizer applications accompanied by frequent watering promote a thick growth of turf and can usually eliminate a cicada killer infestation in one or two seasons. In case of severe infestation, chemical control may be necessary to prevent danger from stinging wasps. Treating the nest area with Sevin (spray or dust) will eliminate the wasps in the treated area.
See better cicada killer photos at the Forestry Images web site at:
http://www.forestryimages.org/browse/subthumb.cfm?sub=2350&start=1
Read more than you will ever care to know about cicada killers at:
http://ww2.lafayette.edu/~hollidac/cicadakillerhome.html
