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Cicada killer wasp
The Cicada Killer Wasp is a large, solitary wasp so named because is hunts cicadas and provisions its nest with them. In North America it is sometimes called the Sand Hornet, although it is not a hornet, which belong to the family Vespidae.
Taxonomy
The North American cicada killer wasps all belong to the genus Sphecius, of which there are 21 species worldwide. The four cicada-killing species in North America are:
- Sphecius speciosus (Drury, 1773), the Eastern Cicada Killer, occurs in the eastern and midwest U.S. and in Mexico and Central America.
- Sphecius convalis (Patton, 1879), the Western Cicada Killer, occurs in the western U.S. and in Mexico.
- Sphecius grandis (Say, 1823), occurs in the mid- and southwest U.S. and in Mexico.
- Sphecius hogardii (Latreille,1806), the Caribbean Cicada Killer, occurs in the U.S. in Florida and in the Caribbean.
The following description concentrates on the North American species.
Description
Adult Cicada Killer Wasps are large, 2/3 to 2 inches (1.5 to 5 cm) long, robust wasps with reddish and black areas on the thorax (middle part) and are marked with various combinations of black, reddish brown and light yellow stripes on the abdominal (rear) segments. The wings are brownish. Coloration may superficially resemble that of yellowjackets or hornets. Queen European hornets (Vespa crabro) are often mistaken for cicada killers.
Life Cycle and Habits
Solitary wasps (such as the Cicada Killer) are very different in their behavior than the social wasps such as hornets, yellowjackets, and paper wasps. Cicada Killer females use their sting to paralyze their prey (cicadas) rather than to defend their nests. Adults feed on flower nectar and other plant sap exudates.
Little is known about the biology of most species of cicada killers; the following account is based on what is known about the Eastern Cicada Killer, Sphecius speciosus. Adults emerge in summer, beginning around July and continuing throughout the summer months. They are present in a given area for 60 to 75 days, until mid-September. They are commonly seen in late summer skimming around lawns, shrubs and trees searching for cicadas. There may be many individuals flying over a lawn, and females may share a burrow, digging their own nest cells off of the main tunnel. A burrow is 15 to 25 cm (6 - 10 in.) deep and about 3 cm (1.5 in.) wide. The female dislodges the soil with her jaws and pushes loose soil behind her as she backs out of the burrow using her hind legs. This action is aided by special spines located on the hind legs. The excess soil pushed out of the burrow forms a mound with a trench in it at the burrow entrance. This ground-burrowing wasp may be found in well-drained, sandy soils to loose clay in bare or grass-covered banks, berms, hills as well as raised sidewalks, driveways and patio slabs. Cicada killers may nest in planters, window boxes, flowerbeds or under shrubs, ground cover, etc. Nests often are made in the full sun where vegetation is sparse, especially in well-drained soils.
After digging a nest chamber in her burrow, the female cicada killer captures cicadas, paralyzing them with a sting; the cicada then serves the insect as food to rear their young. After paralyzing a cicada, the female wasp straddles it and takes off toward her burrow; this return flight to the burrow is difficult for the wasp because the cicada is twice her weight. After putting the cicada in the nest cell, the female deposits an egg on the cicada and closes the cell with dirt. Male eggs are laid on a single cicada but female eggs are given two or sometimes three cicadas; this is because the female wasp is twice as large as the male and must have more food. New nest cells are dug as necessary off of the main burrow tunnel and a single burrow may eventually have 10 to 20 cells. The egg hatches in one or two days, and the cicadas serve as food for the grub. The larvae complete their development in about 2 weeks. Overwintering occurs as a mature larva within an earth-coated cocoon. Pupation occurs in the nest cell in the spring and lasts 25 to 30 days. There is only one generation per year and no adults overwinter.
Interaction with Humans
Female Cicada killer wasps are non-aggressive and rarely sting unless handled roughly, disturbed, or caught in clothing, etc. Males aggressively defend their perching areas on nesting sites against rival males but they have no sting. Although they appear to attack anything which moves near their territories, male cicada killers are actually investigating anything which might be a female cicada killer ready to mate. Such close inspection appears to many people to be an attack, but the wasps never land on people or try to sting or bite. If handled roughly females will sting and both sexes are well equipped to bite with their large jaws.
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