Sphecius speciosus, often simply referred to as the cicada killer or the cicada hawk,
is a large digger wasp species. Cicada killers are large, solitary wasps in the family Crabronidae.
The name may be applied to any species of crabronid which uses cicadas as prey, though
in North America it is typically applied to a single species, S. speciosus. However, since
there are multiple species of related wasps, it is more appropriate to call it the eastern
cicada killer. This species occurs in the eastern and midwest U.S. and southwards into
Mexico and Central America. They are so named because they hunt cicadas and provision their
nests with them. In North America they are sometimes called sand hornets, although they
are not hornets, which belong to the family Vespidae. Cicada killers exert a measure of
natural control on cicada populations and thus may directly benefit the deciduous trees
upon which their cicada prey feed. The most recent review of this species' biology
is found in the posthumously published comprehensive study by noted entomologist Howard Ensign
Evans.
Description
Adult eastern cicada killer wasps are large, 1.5 to 5.0 centimetres long, robust wasps
with hairy, reddish and black areas on the thorax, and are black to reddish brown marked
with light yellow stripes on the abdominal segments. The wings are brownish. Coloration
superficially resembles that of some yellowjacket and hornet species. The females are somewhat
larger than the males, and both are among the largest wasps seen in the Eastern United
States, their unusual size giving them a uniquely fearsome appearance. European hornets are
often mistaken for Eastern cicada killers. Life cycle and habits
Solitary wasps are very different in their behavior from the social wasps such as hornets,
yellowjackets, and paper wasps. Cicada killer females use their sting to paralyze their
prey rather than to defend their nests; unlike most social wasps and bees, they do not attempt
to sting unless handled roughly. Adults feed on flower nectar and other plant sap exudates.
Adults emerge in summer, typically beginning around late June or early July and die off
in September or October. They are present in a given area for 60 to 75 days, usually
until mid-September. The large females are commonly seen skimming around lawns seeking
good sites to dig burrows and searching for cicadas in trees and taller shrubs.
The males are more often seen in groups, vigorously challenging one another for position on the
breeding aggregation from which they emerged, and generally investigate anything that moves
or flies near them. It is not unusual to see two or three male wasps locked together in
apparent midair combat, the aggregate adopting an erratic flight path until one of the wasps
breaks away. The male wasp's aggressive behavior is similar to that of another robust insect
of the area, the male carpenter bee. In both cases, while the males' vigorous territorial
defense can be frightening and intimidating to human passersby, the males pose no danger
whatsoever. They will only grapple with other insects, and cannot sting.
This ground-burrowing wasp may be found in well-drained, sandy soils to loose clay in
bare or grass-covered banks, berms and hills as well as next to raised sidewalks, driveways
and patio slabs. Females may share a burrow, digging their own nest cells off the main
tunnel. A typical burrow is 25–50 centimetres deep and about 1.5 cm wide. In digging a
burrow, the female dislodges the soil with her jaws and, using her hind legs, pushes
loose soil behind her as she backs out of the burrow. Her hind legs are equipped with
special spines that help her push the dirt behind her. The excess soil pushed out of
the burrow forms a mound with a trench through it at the burrow entrance. Cicada killers
may nest in planters, window boxes, flower beds or under shrubs, ground cover, etc. Nests
often are made in the full sun where vegetation is sparse.
After digging a nest chamber in the burrow, female cicada killers capture cicadas, paralyzing
them with a sting. After paralyzing a cicada, the female wasp holds it upside down beneath
her and takes off toward her burrow; this return flight to the burrow is difficult for
the wasp because the cicada is often more than twice her weight. After putting one or
more cicadas in her nest cell, the female deposits an egg on a 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 or more nest 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. This wasp is frequently attacked by the parasitic
"velvet ant" wasp, Dasymutilla occidentalis, also known as the "cow-killer" wasp. It lays
an egg in the nest cell of the cicada killer, and when the cicada killer larva pupates,
the parasitoid larva consumes the pupa. Interaction with humans
Although cicada killers are large, female cicada killer wasps are not aggressive and
rarely sting unless they are grasped roughly, stepped upon with bare feet, or caught in
clothing, etc. One author who has been stung indicates that, for him, the stings are not
much more than a "pinprick". Males aggressively defend their perching areas on nesting sites
against rival males but they have no sting. Although they appear to attack anything that
moves near their territories, male cicada killers are actually investigating anything
that might be a female cicada killer ready to mate. Such close inspection appears to
many people to be an attack, but male and female cicada killers do not land on people
and attempt to sting. If handled roughly, females will sting, and males will jab with
a sharp spine on the tip of their abdomen. Both sexes are well equipped to bite, as they
have large jaws; however, they do not appear to grasp human skin and bite. They are generally
non-aggressive towards humans and usually fly away when swatted at, instead of attacking.
Other Cicada Killer Wasps The North American cicada killer wasps all
belong to the genus Sphecius, of which there are 21 species worldwide. The remaining three
cicada-killing species in the genus in North America are:
Sphecius convallis, the Pacific cicada killer, occurs in the western U.S. and in Mexico.
Sphecius grandis, the western cicada killer, occurs in the mid- and western U.S. and in
Mexico. Sphecius hogardii, the Caribbean cicada killer,
occurs in the U.S. in Florida and in the Caribbean. It is suspected that the western cicada killer
represents more than one species. There is also evidence to suggest that the eastern
cicada killer has either a subspecies or a closely related species that mimics the Pacific
cicada killer. Alternatively, when they were already distinct species, significant hybridization
has occurred between them, though not enough to fully overcome their present reproductive
isolation. The spectacled cicada killer, Sphecius spectabilis,
is found in the South American countries of Argentina, Bolivia, Brazil, Chile, Colombia,
French Guiana, Paraguay, Surinam and Venezuela. Sixteen other cicada killer wasp species in
the genus Sphecius are found in Europe, the Middle East, Africa and Asia. There are also
other genera of cicada-killing wasps which are the "cicada killers" of their native lands.
References
External links
Sphecius is a comprehensive list of taxonomic information on the genus.
Prof. Chuck Holliday's cicada killer page, Dept. of Biology, Lafayette College
Prof. Joe Coelho's cicada killer page Dick Walton's Solitary Wasps Page with outstanding
video clips of Sphecius speciosus and other digger wasps
Australian cicada killers, genus Exeirus Image of Australian cicada killer wasp Exeirus
lateritius Eastern cicada killer on the University of
Florida / Institute of Food and Agricultural Sciences Featured Creatures website
The original version of this heavily edited article was a copy of a fact sheet from the
Ohio State University Extension.