Sphecius grandis

Taxonomy

Order: Hymenoptera
Family: Crabronidae
Subfamily: Bembicinae
Tribe: Gorytini
Genus: Sphecius Dahlbom, 1844
Species: Sphecius grandis (Say, 1823)
Common name: western cicada killer

Common name

western cicada killer

Background

Sphecius grandis is also known as the western cicada killer. It is a species of solitary wasp in the family Crabronidae. It is found in western Central and North America. The taxonomy has been treated by Holliday and Coelho (2006). Little is known about the biology of this species, but what we do know was covered by Coelho et al. (2020). It shares some of the same biology as the more common eastern cicada killer (S. speciosus). Though this species can sting it is not aggressive. They use their venom to paralyze cicadas to take back to their nests and feed their young.

How to separate from NGH

• Cicada killers can be as large or larger than northern giant hornets and are frequently confused with NGH
• The head is smaller in proportion to the body than NGH and the eyes are round (instead of notched)
• This species is dark orange/red with yellow markings

Distribution

Sphecius grandis is endemic to Central America, Mexico, and the western United States. It is generally found at higher elevations than other species of Sphecius.

The distribution of Sphecius grandis by GBIF: https://www.gbif.org/species/7540488

Diagnostic characteristics

• Body length 3–5 cm (1–2 in)
• The body is reddish-brown to black, with yellow bands the metasomal terga 1–5
• The punctation is the same density on metasomal terga 1 and 2, unlike the similarly colored S. convallis (the Pacific cicada killer), where the punctation is less dense in the middle of metasomal tergum 2, than on tergum 1
• Flagellomeres II–IV are bead-like and convex ventrally

Diversity

There are 4 species of Sphecius in North America and 21 species worldwide. The genus occurs in Africa, Eurasia, and North and Central America.

Host/prey associations

Although adult cicada killer wasps feed on nectar from flowers, female cicada killers prey on cicadas to feed their larvae. A female captures and paralyzes a cicada by stinging it in the abdominal region. She then drags the paralyzed cicada into her underground nest where it will be stored as food for the larvae (Alcock 1975).

Nesting and general behavior

Cicada killers build their nests in the ground, and often form aggregations that can contain large numbers of nests. Each nest is provisioned by a single female (Hastings et al. 2008). The nests are built in well-drained, exposed sandy soil, sometimes under sidewalks. The nest entrances are generally located in full sun. A female lays an egg in the body of a cicada and places the cicada in a nest cell. The larva emerges several days later and feeds on the cicada’s body for about two weeks. In the fall, the larva spins a cocoon and pupates during the winter. It emerges from the pupal stage in early to mid-summer as an adult. Females are larger than males and live long enough to produce a brood in July or early August (Drees and Jackman 1998). Many prey cicadas are stolen by birds and other cicada killer females, which enter the burrows of other individuals and lay eggs on the already-provisioned cicada (Coelho et al. 2020).