Nature Notes
by Bob Thomas

The cicada is one of our most common yet innocuous insects that abound in neighborhoods and countryside during the summer. They while away their days singing and breeding, yet from July to September they are savagely attacked by one of our largest native wasps, the cicada killer (Sphecius speciosus).

Cicada killers are very large having a total length of about an inch and a half. Their dark brown or black abdomen is adorned with yellow rings making it a striking beast. This pattern and their frantic buzzing about as they search for prey results in their nickname, the policeman.

They are considered among our worst stinging insects, possibly due to their size and the amount of venom they can inject.

Female cicada killers fly about in yards and along forest edges searching for adult annual cicadas, the type we have that appear each summer. The cicada killers frequently attack the cicadas on the wing and sting them until they become paralyzed. The cicada killers then take their prey to a 12-inch deep tunnel, often containing a right angle about midway down, and deposit them in an expanded chamber at the end. After one to several cicadas are placed in the chamber, the female places an egg on one and plugs the tunnel entrance. The egg hatches and the larva enjoys a living, though immobile, food source. The larva then pupates and emerges in the spring as an adult to repeat the cycle the following summer.

Of extreme interest is that the female cicada killer determines the sex of her offspring. After mating, sperm are stored in little pouches called spermathecae. The female produces a male egg by not fertilizing it, and a female results when she emits sperm from the spermathecae as the egg passes its opening in the oviduct.

Research has shown that when she creates a male, she lays the egg on one immobilized cicada in the tunnel chamber. If a female is produced, she lays the egg on an immobilized cicada that shares the chamber with one or two additional cicadas, thus allowing the females more food for more growth.

Cicada killers spend about 90 percent of their lives as larvae and pupae. Their adult lifespan is only two to six weeks. They are active only one summer season, then they die.

Obviously, the wasp gets its name from its choice of and method of acquiring food for its larvae. The adults, however, feed on nectar as do most bees and wasps.

It is said that this species can be so common that lawns are damaged by an abundance of their tunnels, but the problem is usually highly localized.

During the dog days of summer, keep your eyes pealed for these marvelous and very large predatory wasps.

Also published in Delta Journal, The Times Picayune, September 9, 2007, and September 27, 1989.

A cicada killer (Sphecius speciosus) has                                      The cicada killer flies away with its living,
captured a cicada, its principal prey, and is                                 paralyzed prey. The cicada is placed in a
immobiliziing it with a sting to the thorax.                                   burrow and is destined to be food for a
Photo by Tom Finnie.                                                               cicada killer larva.
                                                                                                 Photo by Tom Finnie.