Cicada Killer

The review of the literature did not reveal any predators of the cicada killer wasp. However, it is likely that these wasps fall prey to birds, small mammals, and other insects.

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 spend most of their lives inside the nest. Young do not reach maturity or leave the nest for 10 to 12 months after the fertilized cicada killer egg is laid inside the cicada. Within two months of emerging from the nest, they will mate, produce offspring, then die.

Range lifespan
Status: wild: 11 to 13 months.

Average lifespan
Status: wild: 13 months.

Range lifespan
Status: captivity: unknown (low) hours.

Typical lifespan
Status: wild: 11 to 13 months.

Average lifespan
Status: wild: 13 months.

Typical lifespan
Status: captivity: unknown (low) hours.

Cicada killer wasps dig nest tunnels in loose, sandy ground. The nests may contain multiple chambers where eggs of different females will be laid. The surface of the nest are is usually well-exposed to sunlight. Cicada killers can be found in forested areas, grasslands, and even in city parks and urban gardens.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: savanna or grassland ; forest ; scrub forest

Other Habitat Features: urban ; suburban

Cicada killer wasps, Sphecius speciosus can be found in almost all parts of North America, especially in areas east of the Rocky Mountains in the United States. Cicada killer wasps can also be found across Europe.

Biogeographic Regions: nearctic (Native ); palearctic (Native )

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 )

Adult cicada killers pollinate flowers when they gather nectar for food. Also, cicada killer wasps helps control the cicada population.

Ecosystem Impact: pollinates

It is unlikely that these wasps provide any direct benefit to human economies. However, humans may benefit from the roles S. speciosus plays in the ecosystem. Cicada killers are pollinators and reduce annoying cicada populations.

Positive Impacts: controls pest population

Cicada killers are capable of stinging humans, and their large size makes them appear threatening to humans. However, these wasps are very passive and rarely attacks humans. The poison associated with a S. speciosus sting is also relatively harmless to humans. Although they are relatively harmless, cicada killers are sometimes viewed as a pest by humans, especially since they disturb lawns with their nests and burrows.

Negative Impacts: injures humans (bites or stings); household pest

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

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

The only known communication amongst cicada killers lies in the buzzing created by the wings of the cicada killer. It is believed that this buzzing is used by males to threaten other males who enter their territory. (Coelho, 1998). However, there is obviously more communication between these wasps which facilitates mating as well as the sharing of burrows by different females which has sometimes been reported.

Communication Channels: acoustic

Other Communication Modes: vibrations

Perception Channels: visual ; tactile ; acoustic

These interesting animals can be viewed in great detail at Professor Chuck Holliay's Cicada-Killer page. Video of many of the activities of these wasps are available there.

The male attempts to attract females that enter his territory. If his courtship is successfull, then the two mate. The exact details of courtship are unknown, but it appears that one male may fertilize multiple females.

Mating System: polygynous

After mating, females begins digging a nest where they will store cicadas as hosts for their eggs, as well as food for the young cicada killers. A female paralyzes and poisons the cicada by catching it in the air and stinging it on its ventral surface. She then drags the cicada back to the nest where she deposits her egg inside it. A female will capture other cicadas, as well, and store them as food for the larva when it emerges from its host. Females have been known to work collectively to construct a single nest with multiple chambers, in which each female will store her egg and cicadas in an individual chamber.

Breeding interval: These wasps live for a single reproductive season, and so only breed once in their lives.

Breeding season: Breeding occurs from July to August.

Range eggs per season: 1 (low) .

Range gestation period: 2 to 4 days.

Average gestation period: 3 to 4 days.

Range age at sexual or reproductive maturity (female): 10 to 12 months.

Average age at sexual or reproductive maturity (female): 12 months.

Range age at sexual or reproductive maturity (male): 10 to 12 months.

Average age at sexual or reproductive maturity (male): 12 months.

Key Reproductive Features: semelparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous

Female cicada killer wasps provide all the parental care for their offspring. They provide a nest and a host for the eggs to be laid in, which serves as food for the larvae when they hatch. Beyond this, adult cicada killers provide nothing for the developing young.

Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female)

U. S. west of 100th meridian; Mexico (Baja California).

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).

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).

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).

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)

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).

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).

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).

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)

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)

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

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).