Pests to know in Rochester
Termites in Rochester
Subterranean termites are uncommon to rare in Minnesota and are generally seen only in the southern third of the state, with swarmers appearing in spring.[1]
Invasive species reported here
- Emerald ash borer was first found in the Rochester area in August 2014 and confirmed inside city limits in 2015, which put Olmsted County in Minnesota's EAB quarantine.[7]
- Rochester has roughly 4,000 inventoried ash trees at risk from emerald ash borer, and the city no longer marks infested private ash until they become high-risk or dead.[7]
Climate
Central Rochester (ZIP 55902) is in USDA plant hardiness zone 4b, where the average coldest winter night is -25 to -20°F.[11]
Public agencies that handle pests
- Olmsted County Public Health Services warns that ticks carrying tick-borne diseases are present in Olmsted County, and recommends staying mid-trail and checking for ticks after outdoor time.[2]
- Olmsted County Public Health Services identifies skunks, bats and raccoons as the wild animals that most commonly carry rabies.[3]
- La Crosse encephalitis, spread by the Eastern Tree Hole mosquito, is found in southeastern Minnesota, especially in counties along the Mississippi River.[4]
- West Nile virus reached Minnesota in 2002, and the state health department says years of dead-bird testing confirmed it is widely established statewide.[6]
Hiring a licensed company
Minnesota law bars anyone from doing structural pest control for hire without a structural pest control license.[8]
Free local help
- Boxelder bugs often go unnoticed in summer but push into Minnesota homes in fall seeking winter shelter. Extension advises vacuuming them indoors rather than spraying.[9]
- Multicolored Asian lady beetles fly to Minnesota buildings between late September and late October on days above 65 degrees, and they do not reproduce indoors.[10]
Through the year
- Summer to Fall
- Most La Crosse encephalitis cases in Minnesota occur from July through September, when infected mosquito populations peak. Buckets, cans and tires that hold water give the tree hole mosquito breeding habitat.[4]
- Spring to Fall
- In Minnesota, adult blacklegged ticks peak in May and return in fall from late September through October; nymphs are most active from late May through June.[5]
Sources
- University of Minnesota Extension, “What insect is this? Subterranean termites.” apps.extension.umn.edu/garden/diagnose/insect/indoor/flies/medium/subterranean-termites.html (accessed 2026-10-06)
- Olmsted County Public Health Services, “Avoid warm weather diseases spread by insects.” www.olmstedcounty.gov/government/county-news-events/press-releases/Avoid-warm-weather-diseases-spread-by-insects (accessed 2026-10-06)
- Olmsted County Public Health Services, “Olmsted County hosts 65th annual rabies vaccination clinic.” www.olmstedcounty.gov/government/county-news-events/press-releases/Olmsted-County-hosts-65th-annual-rabies-vaccination-clinic (accessed 2026-10-06)
- Minnesota Department of Health, “La Crosse Encephalitis Statistics.” www.health.state.mn.us/diseases/lacencephalitis/statistics.html (accessed 2026-10-06)
- Minnesota Department of Health, “Ticks.” www.health.state.mn.us/diseases/tickborne/ticks.html (accessed 2026-10-06)
- Minnesota Department of Health, “West Nile Virus (WNV).” www.health.state.mn.us/diseases/westnile/index.html (accessed 2026-10-06)
- City of Rochester, “Emerald Ash Borer.” www.rochestermn.gov/home-property-utilities/trees-lawns-forestry/invasive-species/emerald-ash-borer/ (accessed 2026-10-06)
- Minnesota Office of the Revisor of Statutes, “18B.32 Structural Pest Control License.” www.revisor.mn.gov/statutes/cite/18B.32 (accessed 2026-10-06)
- University of Minnesota Extension, “Boxelder bugs.” extension.umn.edu/garden-and-home/home-maintenance/household-insects/boxelder-bugs (accessed 2026-10-06)
- University of Minnesota Extension, “Multicolored Asian lady beetles.” extension.umn.edu/garden-and-home/yard-and-garden/yard-and-garden-insects/multicolored-asian-lady-beetles (accessed 2026-10-06)
- USDA ARS and PRISM, via phzmapi.org, “Plant hardiness zone for ZIP 55902 (2023 USDA map data).” phzmapi.org/55902.json (accessed 2026-10-06)
- National Pesticide Information Center, “State Pesticide Regulatory Agencies.” npic.orst.edu/reg/state_agencies.html (accessed 2026-10-06)