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Pests and pest control in Montana

Pests to know in Montana

Why each one matters here is cited in the sections below.

Pests documented in Montana

From public GBIF occurrence records since 1990. A record means a species was documented in Montana, not that it's common near you.

Many public records (303)

Fewer public records (205)

Range named by extension sources (2)

Invasive species reported here

Japanese beetle, which can devastate lawns and landscape plants, arrived in Montana near the Billings airport, likely by hitchhiking on air cargo flights.[2]

Pests local experts flag

  • The western black widow is common in Montana and is, to date, the only spider of medical importance in the state; the brown recluse is not native to Montana.[3]
  • The Rocky Mountain wood tick is found on livestock, pets and people in Montana in spring and summer, while the blacklegged ticks that carry Lyme disease have not become established in the state.[4]
  • Cluster flies can gather by the hundreds on the sunny sides of Montana buildings in late fall and enter through attics to overwinter.[6]

Public agencies that handle pests

Montana DPHHS runs West Nile virus surveillance, trapping and testing mosquito pools in counties across the state as an early warning system and mapping detections each season.[7]

Hiring a licensed company

Montana's pesticide regulatory agency is the Montana Department of Agriculture (Pesticide Programs).[1]

Licensing agency: Montana Department of Agriculture — Pesticide Programs[1].

See also how to check a pest control license.

Free local help

MSU Extension's Schutter Diagnostic Lab diagnoses plant diseases and insect damage and identifies insects and other arthropods, and residents can email photos first.[8]

Local guides in Montana

Through the year

Summer to Fall
Hobo spiders enter Montana homes from August through November, and populations can be very high in basements, especially in central and western Montana.[3]
Spring to Summer
Miller moths are a nuisance in Montana in May and June as they pass through on migrations from the eastern plains to higher elevations.[5]

Sources

  1. National Pesticide Information Center, “State Pesticide Regulatory Agencies.” npic.orst.edu/reg/state_agencies.html (accessed 2026-10-06)
  2. Montana Department of Agriculture, “Pests.” agr.mt.gov/Pests (accessed 2026-10-06)
  3. Montana State University Extension Urban IPM, “Urban Spiders.” urbanipm.montana.edu/entomology/resources/fact-sheets/spiders_of_montana/urban_spiders_ipm.html (accessed 2026-10-06)
  4. Montana State University Extension Urban IPM, “It's Tick Season.” urbanipm.montana.edu/entomology/resources/fact-sheets/its_tick_season.html (accessed 2026-10-06)
  5. Montana State University Extension Urban IPM, “Miller Moths.” urbanipm.montana.edu/entomology/resources/fact-sheets/spiders_of_montana/miller-moths.html (accessed 2026-10-06)
  6. Montana State University Extension Urban IPM, “Cluster Flies.” urbanipm.montana.edu/entomology/resources/fact-sheets/nuisance_insect_pests/cluster.flies.html (accessed 2026-10-06)
  7. Montana Department of Public Health and Human Services, “West Nile Virus.” dphhs.mt.gov/publichealth/cdepi/diseases/westnilevirus (accessed 2026-10-06)
  8. Montana State University Extension, “Schutter Diagnostic Lab.” diagnostics.montana.edu/ (accessed 2026-10-06)

Updated 2026-10-06. Every statement on this page comes from the cited state, federal or university source. Spot an error? Tell us.