Pest profile

Sclerodermus Wasps

Sclerodermus species (S. carolinensis, S. macrogaster and S. ventura in North America) · Hymenoptera: Bethylidae[2]

Sclerodermus are tiny, ant-like flat wasps that parasitize wood-boring beetle larvae; when they share infested furniture or rafters with people, the females can sting.[1]

Wingless Sclerodermus wasp, reddish brown and ant-like with a large head and darker abdomen
Wingless Sclerodermus wasp, reddish brown and ant-like with a large head and darker abdomen. Photo: Jesse Rorabaugh, public domain (CC0), via iNaturalist

How to identify it

  • They're 1.5 to 6 mm (0.05 to 0.25 inch) long, flattened and ant-like, with a large, boxy head and a long, tapered abdomen.[1]
  • Most are wingless females, though both sexes can be winged or wingless.[1]
  • S. carolinensis is light to dark reddish brown; S. macrogaster has cream patches on the thorax; S. ventura has a light red head and thorax and a dark brown abdomen.[1]

Where it lives

Three species occur in North America: S. carolinensis from Connecticut and Illinois to Georgia and Louisiana, S. macrogaster from Virginia to Texas and southward, and S. ventura in California.[1]

US map: public records from 17 states since 1990 (GBIF).

Biology and life cycle

They parasitize wood-boring beetle larvae, including longhorn beetles, metallic wood borers, death-watch beetles and bark beetles.[1]

Females cooperate to subdue large larvae and help raise each other's young, laying 5 to 120 eggs per host.[1]

Females can live up to seven months; an unmated female can raise sons, mate with them and then produce daughters.[1]

Damage and signs

  • Large infestations can send dozens of wasps a day into living space as females search for new hosts.[1]
  • Most known infestations are in Europe, especially Italy; Penn State's review reports only one US case.[1]

Health risk

Females sting when picked up or trapped in clothing; a pinprick pain becomes a red, itchy welt that usually clears in 5 to 15 days, sometimes with mild fever or nausea.[1]

Control

Traps and physical control

Stings stop only when the infestation is found and removed; infested furniture or cabinetry can simply be taken out of the home.[1]

When to call a professional

When beetles and wasps are in rafters or framing, repeated insecticide treatments or fumigation by a licensed pest control operator may be needed.[1]

Common questions

What tiny wasp is stinging me indoors?
If old furniture or wood framing has wood-boring beetles, it may be Sclerodermus, which hunts those beetle larvae.[1]
How are Sclerodermus stings treated?
Penn State notes that topical corticosteroids and antihistamines effectively treat the symptoms.[1]

Sources

  1. Penn State Extension, “Sclerodermus, a Small Wasp that Occasionally Infests Homes.” extension.psu.edu/sclerodermus-a-small-wasp-that-occasionally-infests-homes (accessed 2026-10-06)
  2. iNaturalist, “Sclerodermus taxon page (order and family).” www.inaturalist.org/taxa/212140 (accessed 2026-10-06)

Updated 2026-10-14. Built from sourced records. Spot an error? Tell us.