Identification

Scary-looking but harmless insects

Many of the insects people call about are harmless to people, and several are beneficial. A few can bite or sting if picked up, and one, the blister beetle, can blister skin, so the rule is simple: look, don't handle.[4][7][17]

The short answer

  • Crane flies aren't giant mosquitoes and don't eat mosquitoes; they're medically harmless.[4]
  • Periodical cicadas can't sting and don't harm people, livestock or pets, though egg-laying females can damage young trees.[3]
  • Velvet ants are wingless female wasps with a very painful sting; giant water bugs, stag beetles and robber flies can bite if handled.[15][12][13][14]
  • Blister beetles contain cantharidin, which blisters skin and can make horses that eat contaminated hay extremely ill or kill them.[17]

Cicadas

Cicadas have bulging eyes and clear wings held roof-like over large bodies; the larger annual (dog-day) cicadas are about 1-5/8 inches long and appear in late summer. Males sing from tree trunks and branches; females don't sing. Nymphs feed on sap from tree roots and leave 1/2-inch exit holes in the ground.[2]

  • Periodical cicadas have black bodies, red eyes and orange wing veins and emerge in huge broods every 13 or 17 years in the eastern U.S., mostly from late April through June.[3]
  • Females slit 1/4- to 1/2-inch twigs to lay eggs, so twig tips break and turn brown (flagging). Delay new plantings until the emergence ends, and cover young trees with netting or cheesecloth, secured around the trunk, as soon as males start singing; insecticides are of limited use.[3]

Crane flies and mayflies

  • Crane flies are large, tan, fragile, long-legged flies. Adults don't feed, and larvae eat decaying organic matter; large numbers indoors are a nuisance only.[4]
  • Mayflies hold their large, triangular wings upright over the body and have long tail filaments. Mass emergences near lakes and rivers can pile up under lights at night, but they're medically harmless and an important food for fish.[5]
  • Most mayfly problems happen when the swarms are attracted to electric lights at night.[5]

Harmless and helpful

  • Fireflies are beetles, not flies. Their larvae eat small insects, earthworms, slugs and snails, and they're medically harmless.[6]
  • Antlion larvae dig funnel-shaped pits in sand, up to 2 inches across, to trap ants; adults look like drab damselflies with clubbed antennae. They're beneficial and medically harmless.[7]
  • Barklice are tiny insects that live under silken webbing on tree bark, feeding on fungi, algae and debris. By late summer the webbing can wrap a whole tree, but they're harmless to the tree and to people.[8]
  • Water boatmen swim in groups in ponds and eat plant material and algae; they're beneficial fish food and medically harmless.[9]
  • Walkingsticks are slow, wingless, stick-like insects up to about 4 inches long; they eat leaves of trees such as oak, pecan and wild cherry and occasionally defoliate trees in cyclic outbreaks.[10]
  • Monarch caterpillars, ringed in black, yellow and white, feed on milkweed and are medically harmless.[11]

Mining bees and sweat bees in the lawn

  • Many small mounds with holes in a sunny, thin patch of lawn in spring are usually solitary ground-nesting bees: mining bees, often black with reddish hair, or tiny, often metallic sweat bees. Each female digs her own burrow 6 inches or more deep.[1]
  • They're important pollinators, damage turf only slightly, and solitary bees have no mass-attack behavior like honey bees or yellowjackets; insecticide treatment is almost never necessary.[1]
  • To discourage nesting, water the area heavily, add organic matter, and grow dense turf or mulch bare spots.[1]

Harmless unless handled

  • Giant water bugs, over 2 inches long and called electric light bugs because they fly to lights, aren't pests but can give a painful bite if handled. Water scorpions are related long-legged aquatic predators that look a bit like slender praying mantises.[12]
  • Stag beetles, 1 to 1-1/2 inches with long jaws on the males, develop in decaying wood and come to lights; they may bite if handled.[13]
  • Robber flies are hairy, often bee-like predatory flies that catch other insects in the air; they can bite painfully if mishandled.[14]
  • Velvet ants, or cow killers, are wasps, not ants: the red velvet ant is about 3/4 inch, black with dense orange-red hair. Wingless females, often seen running over sandy ground in summer, can sting painfully; winged males can't sting.[15]
  • Leafcutting bees cut neat circles from rose and other leaves to line their nests. They're important pollinators, nest in hollow twigs or holes in buildings, and females can sting.[16]
  • Blister beetles are long, narrow beetles that feed in swarms on leaves, especially legumes. Don't handle them; their cantharidin raises blisters.[17]

Common questions

Are crane flies dangerous?
No. Adults don't feed and don't bite, and they don't eat mosquitoes despite the name mosquito hawk.[4]
Do cicadas bite or sting?
Periodical cicadas can't sting and don't harm people or pets.[3]
Is a velvet ant really an ant?
No, it's a wasp. The wingless females can sting painfully, which gave them the name cow killer.[15]

Sources

  1. NC State Extension, “Ground-Nesting Bees in Turf (TurfFiles).” www.turffiles.ncsu.edu/insects/bees-in-turf/ (accessed 2026-10-06)
  2. Texas A&M AgriLife Extension, “Dog-Day Cicada (Field Guide to Common Texas Insects).” texasinsects.tamu.edu/dog-day-cicada/ (accessed 2026-10-06)
  3. University of Kentucky Entomology, “ENTFACT-446: Periodical Cicadas in Kentucky.” entomology.mgcafe.uky.edu/ef446 (accessed 2026-10-06)
  4. Texas A&M AgriLife Extension, “Crane Fly (Field Guide to Common Texas Insects).” texasinsects.tamu.edu/crane-fly/ (accessed 2026-10-06)
  5. Texas A&M AgriLife Extension, “Mayfly (Field Guide to Common Texas Insects).” texasinsects.tamu.edu/mayfly/ (accessed 2026-10-06)
  6. Texas A&M AgriLife Extension, “Firefly (Lightning Beetle) (Field Guide to Common Texas Insects).” texasinsects.tamu.edu/firefly/ (accessed 2026-10-06)
  7. Texas A&M AgriLife Extension, “Antlion (Field Guide to Common Texas Insects).” texasinsects.tamu.edu/neuroptera/antlion/ (accessed 2026-10-06)
  8. Texas A&M AgriLife Extension, “Barklice (Field Guide to Common Texas Insects).” texasinsects.tamu.edu/psocoptera/barklice/ (accessed 2026-10-06)
  9. Texas A&M AgriLife Extension, “Water Boatman (Field Guide to Common Texas Insects).” texasinsects.tamu.edu/water-boatman/ (accessed 2026-10-06)
  10. Texas A&M AgriLife Extension, “Walkingsticks (Field Guide to Common Texas Insects).” texasinsects.tamu.edu/walkingsticks/ (accessed 2026-10-06)
  11. Texas A&M AgriLife Extension, “Monarch Butterfly (Field Guide to Common Texas Insects).” texasinsects.tamu.edu/monarch-butterfly/ (accessed 2026-10-06)
  12. Texas A&M AgriLife Extension, “Giant Water Bug (Field Guide to Common Texas Insects).” texasinsects.tamu.edu/water-bug/ (accessed 2026-10-06)
  13. Texas A&M AgriLife Extension, “Stag Beetle (Field Guide to Common Texas Insects).” texasinsects.tamu.edu/stag-beetle/ (accessed 2026-10-06)
  14. Texas A&M AgriLife Extension, “Robber Fly (Field Guide to Common Texas Insects).” texasinsects.tamu.edu/robber-fly/ (accessed 2026-10-06)
  15. Texas A&M AgriLife Extension, “Red Velvet Ant or Cow Killer (Field Guide to Common Texas Insects).” texasinsects.tamu.edu/red-velvet-ant-or-cow-killer/ (accessed 2026-10-06)
  16. Texas A&M AgriLife Extension, “Leafcutting Bee (Field Guide to Common Texas Insects).” texasinsects.tamu.edu/leafcutting-bee/ (accessed 2026-10-06)
  17. Texas A&M AgriLife Extension, “Blister Beetle (Field Guide to Common Texas Insects).” texasinsects.tamu.edu/hemiptera/blister-beetle/ (accessed 2026-10-06)

Updated 2026-10-06. Built from sourced records. Spot an error? Tell us.