Bicyrtes

Lepeletier, 1845

Species Guides

7

Bicyrtes is a of large, often brightly colored predatory sand wasps in the Crabronidae. The genus name derives from the two noticeable projections arising from the rear of the mesosoma. Most nest in sandy or coarse soils and provision their burrows with paralyzed true bugs, primarily Pentatomidae (stink bugs), though some species utilize Reduviidae (assassin bugs) and Coreidae (leaf-footed bugs) as prey. The genus contains approximately 11 described species distributed across North America, with some species extending into Central and South America and the Caribbean, including the Galápagos Islands.

Bicyrtes ventralis by (c) christine123, some rights reserved (CC BY), uploaded by christine123. Used under a CC-BY license.Bicyrtes by (c) bg1159, some rights reserved (CC BY), uploaded by bg1159. Used under a CC-BY license.Bicyrtes quadrifasciatus by (c) botanygirl, some rights reserved (CC BY), uploaded by botanygirl. Used under a CC-BY license.

Pronunciation

How to pronounce Bicyrtes: /bɪˈsaɪrtiːz/

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Identification

Bicyrtes can be distinguished from similar sand wasps by the boxy, angular appearance of the (mesosoma), with two noticeable projections arising from the rear corners—giving the its name meaning "two-humped." The angular hind corners of the thorax are often marked with white. The overall body is large and often brightly colored with contrasting patterns. Unlike the more rapidly moving Bembix and Steniolia, Bicyrtes are relatively sedate and approachable when foraging at flowers.

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Habitat

Sandy or coarse-textured soils suitable for burrowing, including areas with pavement fragments and pebbles. Nesting sites include open ground, sand volleyball courts, children's sandboxes, and areas along waterways. frequent flowers for nectar, particularly Dogbane (Apocynum), Indian Hemp, milkweeds (Asclepias), white sweet clover (Melilotus albus), and wild carrot (Daucus carota).

Distribution

North America from southern Canada through the United States; some extend into Central and South America and the Caribbean. Bicyrtes variegatus has been recorded on seven islands in the Galápagos archipelago since 1964. Records exist from Vermont, Massachusetts, and throughout the eastern and central United States west to Texas and Kansas.

Seasonality

Active during warmer months; observed from spring through autumn depending on latitude. In the southern Great Plains and subtropical regions, activity extends longer into the year. Males are active earlier in the season than females.

Diet

feed on nectar from various flowering plants. Females provision nest with paralyzed true bugs (Hemiptera: Heteroptera), primarily Pentatomidae (stink bugs), with some also using Reduviidae (assassin bugs) and Coreidae (leaf-footed bugs). Specific prey records include (Pentatomidae), grasshoppers (Acrididae), and katydids (Tettigoniidae) for at least some species.

Life Cycle

Solitary nesting; females construct burrows 15-51 cm long at shallow angles, terminating in single or multiple . Females stockpile prey () rather than practicing , laying a single on the first prey item placed in a cell. The burrow is closed during hunting excursions and permanently sealed upon completion. Larvae develop on the cached prey. Cocoon has been described for at least B. variegatus.

Behavior

Females are excellent diggers, using a "tarsal rake" of spines on the front to excavate burrows. They use subtle landmarks to relocate hidden nest entrances. Males engage in "sun dances"—level in circles, figure eights, or sinuous patterns—often forming tight clusters referred to as "mating balls" during the hot season. Both sexes are easily approached when distracted by nectar feeding at flowers. Unlike many sand wasps, Bicyrtes tends to nest solitarily rather than in dense , though multiple females may occur in the same general vicinity.

Ecological Role

of true bugs, particularly stink bugs (Pentatomidae), including agricultural pests such as the Brown Marmorated Stink Bug (Halyomorpha halys). Serves as a potential agent for pest . function as through nectar feeding at diverse flowering plants. The is parasitized by velvet ants (Mutillidae), including Traumatomutilla ocellaris recorded from B. variegatus.

Human Relevance

Potential biocontrol agent for agricultural pests. Non-aggressive; solitary females do not defend nests and stings are unlikely. Sometimes mistaken for more aggressive such as , causing unnecessary concern. Presence can be encouraged by preserving sandy nesting sites and avoiding use.

Similar Taxa

  • StictiaBoth are large, brightly colored sand wasps, but Stictia (including the 'Horse Guard' S. carolina) specializes in hunting horse flies (Tabanidae) rather than true bugs, and has different thoracic structure without the two projections.
  • BembixSimilar size and coloration, but Bembix are more rapidly moving, have different thoracic shape without the angular projections, and typically provision nests with flies rather than true bugs.
  • BembecinusSmaller size (8-10 mm vs. larger Bicyrtes), convergent at bottom of , second submarginal in forewing, and practices rather than of prey.

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