The Eastern Cicada Killer (Sphecius speciosus) has been reported from nearly all states in the United States east of the continental divide, as well as southern Ontario (Canada) to the north and Guatemala, Honduras, and northeastern Mexico to the south (Holliday & Coelho 2006). Females dig nest burrows in well-drained soil, often forming large nesting aggregations, and provision nest cells with cicadas they capture and paralyze in nearby trees. Several studies have found that the number of cicadas provided to each offspring is fairly consistent, with sons given 1 (sometimes 2) cicadas and daughters given 2 (sometimes 3) cicadas regardless of cicada size. (Hastings et al. 2010 and references therein). Females are generally larger than male-- often over 4 cm in length--and they can provision their nests with cicadas more than 2.5 times their size (Coelho 1997).
Sphecius speciosus is known to capture cicadas of 5 genera (Diceroprocta, Magicicada, Neocicada, Quesada, Tibicen), including more than two dozen species/subspecies (D. cinctifera, D. olympusa, D. viridifascia, and D. vitripennis; Magicicada cassinii and M. septendecim; Neocicada hieroglyphica and N. h. johannis; Quesada gigas; Tibicen auletes, T. canicularis, T. davisi, T. dealbatus, T. dorsatus, T. figuratus, T. linnei, T. lyricen, T. lyricen engelhardti, T. lyricen virescens, T. pruinosus, T. resh, T. resonans, T. robinsonianus, T. similaris, T. tibicen, T. tibicen australis, T. walkeri, T. walkeri pronotalis, and T. winnemanna). Five species of Tibicen (T. canicularis, T. linnei, T. lyricen, T. pruinosus, and T. tibicen [including T. chloromerus, a junior synonym of T. tibicen] are captured most frequently by S. speciosus, together accounting for 88% of specimens taken. (Holliday et al. 2009)
Available data indicate no significant overall prey sex bias. However, Holliday et al. (2009) found that at sites where more than 50 cicada prey were recorded, the male to female ratio of 6 species brought to nests by Sphecius females varied between 0.524 and 2.259. At these sites, chi-square analysis revealed a significant male bias in overall prey sex ratio. The reported significant local variations in prey sex ratios are likely to be due to temporal variations in sex ratios of cicadas available to these opportunistic wasps. (Holliday et al. 2009)
Hastings et al. (2010) studied size-specific provisioning in S.speciosus in northern Florida. They found that individual female cicada killers at these locations exhibited size-specific prey selection. Small wasps brought only small cicadas to their nests, probably because they are unable to carry large cicadas in flight. Large wasps, which are not as constrained in this way, rarely provision their nests with small cicadas. It appears that these wasps selectively hunt the largest prey they can carry in flight. (Hastings et al. 2010) In contrast to the findings of Hastings et al, however, some previous studies in other areas have concluded that female S. speciosus hunted opportunistically, without regard to prey size. (Coelho 1997; Grant 2006). Hastings et al. suggest that this discrepancy may be explained at least in part by the fact that at these other locations the available prey were relatively uniform in size.
DNA sequence analyses by Hastings et al. (2008) have raised the possibility that S. convallis and S. speciosus may not actually be distinct species
Regularity: Regularly occurring
Type of Residency: Year-round
Regularity: Regularly occurring
Type of Residency: Year-round
Sphecius speciosus has been reported from Canada (Ontario), Guatemala, Honduras, Mexico (Chihuahua, Coahuila, Nuevo Leon), and the following 39 of the 41 states east of the continental divide plus Washington, D.C. and Arizona (apparently not yet reported from Vermont and Michigan): Alabama, Arkansas, Colorado, Connecticut, Delaware, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Minnesota, Maine, Mississippi, Missouri, Montana, Nebraska, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Virginia, Wisconsin, West Virginia, and Wyoming (Holliday and Coelho 2006).
The eastern cicada killer (Sphecius speciosus) occurs throughout the east coast, southeast, and Midwestern U.S. states at high densities. Its range extends much farther west, but with records much less common and none west of the continental divide. It is found throughout Texas, Oklahoma, Kansas, Nebraska and South Dakota, as well as eastern portions of New Mexico, Colorado, Wyoming, and Montana. S. speciosus appears to be excluded from the northern Appalachians and other high altitude regions. Other members of the genus Sphecius occur in the Western U.S., Mexico, Central and South America (Holliday and Coelho, 2006; Coelho, Holliday and Hastings, unpublished).
Females are approximately twice the size of males, on average, by a large number of measurements including body mass and head width. There is considerable variation in size, however, and some overlap between the largest males and smallest females. Females have a very large pair of spurs at the junction of the tibia and tarsus. These spurs function in the digging of the burrow. Females without spurs dig only half as fast as those with intact spurs (Coelho et al., 2008; Coelho and Holliday, 2008; Coelho and Wiedman, 1999).
Cicada killer wasps range from 30 to 50 mm in length. They have a rusty colored head and thorax with bands of alternating yellow and black colors on the abdomen. Cicada killers have six legs that range from yellow to red in color. They also have large dark-colored wings. Females are equipped with a stinger at the end of the abdomen.
Range length: 30 to 50 mm.
Average length: 30 to 40 mm.
Range wingspan: 30 to 40 mm.
Average wingspan: 40 mm.
Other Physical Features: ectothermic ; bilateral symmetry
Cicada killers nest primarily in disturbed areas. Lawns and flower beds are often preferred, much to the chagrin of homeowners. The open soil apparently allows the females to return to the burrow unhindered by overlying vegetation. Digging burrows may be easier with less root mass below ground. Female cicada killers will dig in nearly any kind of soil, but digging is faster in sand. The nest must be reasonably close to trees where cicadas live. The largest nesting aggregation recorded was on the nonvegetated berms of a chemical manufactory, with approximately 5000 burrows present (Hastings et al., 2008).
Although adult cicada killer wasps feed on nectar from flowers, their larvae feed on cicadas. Female cicada killers hunt for cicadas and paralyze them by stinging them in the abdominal region. She then drags the paralyzed cicada back to the underground nest where it will be stored as food for the larvae.
Animal Foods: insects
Plant Foods: nectar
Foraging Behavior: stores or caches food
Primary Diet: carnivore (Insectivore ); herbivore (Nectarivore )
Flowering Plants Visited by Sphecius speciosus in Illinois
(observations are from Robertson and Hilty; this is the 'Cicada Killer' wasp)
Apiaceae: Cicuta maculata sn fq (Rb); Asclepiadaceae: Asclepias incarnata [plpr sn fq] (Rb), Asclepias incarnata [unsp sn] (H); Cucurbitaceae: Sicyos angulatus sn (Rb)
Cicada killers seldom visit flowers. They are frequently found feeding from slime flux, an infected site on a tree or large plant which oozes fermenting sap. This food source probably provides much needed carbohydrate fuel and water.
Very large nesting aggregations may deplete local cicada populations, but this effect has never been conclusively demonstrated.
The burrowing action of the female cicada killer may provide aeration and mixing of the soil (Clark, 1937; Rau and Rau, 1918; Manee, 1915; Hungerford and Williams. 1912).
Parasites and predators
Rarely, birds will attack adult cicada killers. More often, birds attempt to steal the paralyzed cicada from a provisioning female, sometimes successfully. Observations of even this behavior are quite rare. The larvae are much more vulnerable. Commonly, satellite flies will follow the provisioning wasp down into the burrow and lay eggs (or larvae) on the cicada. The fly larvae eat the cicada while the wasp larva perishes. Cicada killer larvae and pupae may also die from mold (Dambach and Good, 1943).
Life History and Behavior
Both males and females are capable of producing a loud buzz. For females, the buzz is primarily defensive. If disturbed in their burrows, females, surprisingly, do not often fly out to sting the intruder. More often they remain in the burrow and produce the buzz. The buzz of the female is louder and has a lower frequency than that of males because females are larger. The buzz may be the only effective defense for females because, like most members of their family, cicada killers have extremely weak stings.
Males produce the buzz when grappling with each other during territorial defense, and also in the mating cluster. Because the frequency of the buzz is proportional to body size, it is possible that males are able to assess the size of other males during such conflicts. Such perception is likely to be possible only during close contact via near-field effects or vibration, as ears have not been demonstrated in cicada killers.
Males have no stinger, but will pretend to sting (pseudosting) while making the buzz, which is likely to be a deterrent to predators.
Buzzing is produced by vibration of the thorax via the flight muscles. The wings act as sounding boards, but are not essential to sound production. The sound has many harmonics, variable frequency, and buzz pulses. Buzzing results in rapid endothermic warm-up, but wasps stop buzzing when they reach too high a body temperature (Coelho, 1998)
Adult female cicada killers lay their eggs in July or August. A female implants an embryo inside the body of a cicada, and stores this in a cell in the nest. The larva emerges several days later and feeds on the cicada's body for about two weeks. In the fall, the larva spins a coccoon, in which it spends the winter hibernating. The larva pupates in the spring, and emerges from the pupal stage in early- to mid-summer as an adult cicada killer. Then, it procedes to acquire food and reproduce. Males die after mating, and females die after laying their eggs. by mid- to late- August, all adults die. Each generation of cicada killers lives only a single year.
Development - Life Cycle: metamorphosis ; diapause
Females are equipped with a pair of shovel-like mandibles and stout legs. The burrow is begun by chewing a hole into the substrate, then kicking the dirt out with the legs while backing up. Females have a pair of large spurs on each hind limb that may assist in kicking dirt out of the hole. Burrows may extend several feet beneath the surface, and have many branches and cells for holding cicadas and larvae. In the end, a large pile of soil (tumulus) accumulates next to a hole about 2 cm in diameter. Females dig quickly enough to complete the main tunnel of a burrow overnight. After completing the burrow, the female makes numerous circular flights of increasing diameter to orient to the burrow entrance.
In many populations, two cicadas are used to provision a cell that will contain a female egg, and one cicada for a cell that will contain a male. The female controls the sex of the offspring by either fertilizing the egg with stored sperm to make it female or not doing so to make it male.
A female flies out and inspects trees until she finds a cicada. After she stings it, the cicada becomes paralyzed within one minute. The wasp then grasps the base of the wings of the cicada with her middle legs, and flies with the cicada in an upside-down position back to her burrow. Females sometimes cannot lift a heavy cicada upward in flight and may have to carry the cicada up another tree on foot, then fly down toward the burrow. If the female lands some distance away, she may have to bear the prey overland to reach it. The female drags the prey down into the burrow.
The cicada killer's venom preserves the cicada, which will live in a paralyzed state twice as long as an unstung, unfed cicada. Within two weeks the larvae have eaten the paralyzed cicadas and grown into prepupae, the form in which they will spend the winter. (Coelho and Holliday, 2008; Bringer, 1996; Dambach and Good, 1943; Dow, 1942)
Territoriality and Mating
Males stake out territories where females are likely to emerge, defending the airspace within their territories against conspecific males, and chasing anything that flies on the chance that it might be a virgin female. Males generally perch in a typical posture on some object within the territory.
Soon after virgin females emerge, they mate, but only once. The male occupying the territory in which the female emerges is usually successful in mating her. They fall to the ground and couple. Other males may try to horn in, forming a cluster around the mating pair. The pair may fly off and land elsewhere. Copulation takes 30-60 minutes. (Hastings et al., 2008; Coelho and Holliday, 2000; Lin, 1966; 1967)
Molecular Biology and Genetics
Barcode data: Sphecius speciosus
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Sphecius speciosus
Public Records: 15
Specimens with Barcodes: 15
Species With Barcodes: 1
Cicada killers are widespread and in little danger of extinction. Thus, currently their survival is not considered threatened.
US Federal List: no special status
CITES: no special status
National NatureServe Conservation Status
Rounded National Status Rank: NNR - Unranked
Rounded National Status Rank: NNR - Unranked
Relevance to Humans and Ecosystems
Female cicada killers appear very imposing because of their large size, aposematic coloration, and loud buzz. Females can sting, but they almost never do. They are nonaggressive, so to be stung one must do something very unwise, such as grasping a female with bare hands. Even so, the sting of this species is very weak, less painful than that of a sweat bee. The venom is not very toxic (Schmidt, 1990), and deaths due to allergic reaction are rumored but unconfirmed. Nonetheless, cicada killers are often perceived as pests by those with large infestations in their yards, and people will go to great lengths and expense to eliminate them (Tashiro, 1987). A ball park and a city park have been closed due to infestation. There is no established method for the long-term control of cicada killers, though many methods are effective at reducing their numbers in the short term (Coelho, 2009).
Cicada killers may reduce the population sizes of cicadas, but the degree of this effect is unknown. Futhermore, the annual cicadas taken by the wasps do not have the impact on trees that periodical cicadas (which emerge too early in the summer) do. The burrows of females may aerate and mix the soil. Cicada killers may be considered aesthetically attractive. They are valuable for entertainment and education. They have been useful scientific models, with nearly 100 references on them (Coelho 2009).
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 preys on cicadas, 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.
Adult eastern cicada killer wasps are large, 1.5 to 5.0 centimetres (0.6 to 2.0 in) long, robust wasps with hairy, reddish and black areas on the thorax (middle part), and are black to reddish brown marked with light yellow stripes on the abdominal (rear) 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 (Vespa crabro) are often mistaken for Eastern cicada killers.
Life cycle and habits
Solitary wasps (such as the eastern cicada killer) 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 (cicadas) 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 (10–20 in) deep and about 1.5 cm (0.59 in) 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 (Taschenberg, 1875), 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 (e.g., Liogorytes in South America and Exeirus in Australia) which are the "cicada killers" of their native lands.
- Howard Ensign Evans & Kevin M. O'Neill (2007). The Sand Wasps: Natural History and Behavior. Harvard University Press. pp. 37–43. ISBN 978-0-674-02462-5.
- Joseph R. Coelho (1998). "Cicada killer control". Retrieved July 18, 2008.
- Jon M. Hastings, Patrick J. Schultheis, Maggie Whitson, Charles W. Holliday, Joseph R. Coelho & Angela M. Mendell (2008). "DNA barcoding of new world cicada killers (Hymenoptera: Crabronidae)" (PDF). Zootaxa 1713: 27–38.
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