Flies
most searchedPeaks in Jun, Jul, Aug, Sep
Kitchens, fruit bowls, drains, garbage cans, compost
Mountain & West · State guide
Pests in Colorado
High-altitude semi-arid. Cold dry winters, hot dry summers, and huge elevation differences that change the pest list over short distances. The single most-searched pest in Colorado is Flies. Below: what drives pressure here, when each pest peaks, and the prevention steps that matter most in this climate.
- 6
- pests tracked
- 6
- have a peak month
- 22
- guides linked
- 3b–7a
- hardiness zone
[ 01 ] Most searched
The most-searched pest in Colorado
Based on Google search interest across 30 common household pests. Source: Organic Lesson, “The Most Troublesome Household Pests in Each State,” Google Trends analysis of 30 common household pests, reported by Pest Control Technology
Flies
- Looks like
- One pair of wings; fruit flies tan with red eyes, drain flies fuzzy and moth-like
- Where you find it
- Kitchens, fruit bowls, drains, garbage cans, compost
- Size
- 1/16 to 1/4 inch (1.5–6 mm)
- Health risk
- moderate
Signs in the home
- Small flies around ripe fruit or the sink
- Flies resting on bathroom walls near drains
- Maggots in garbage bins
Start here
[ 02 ] Local pressure
Pests that drive pressure in Colorado
Each bar shows twelve months of seasonal activity. Bars come from the same dataset as the pest activity index, so the months here always match the months there.
Ants
Peaks in May, Jun, Jul, Aug
Kitchens, bathrooms, wall voids, lawn mounds, damp or rotting wood
Wasps & Yellow Jackets
Peaks in Jun, Jul, Aug, Sep
Eaves, sheds, playsets, wall voids, ground holes (yellow jackets)
Bees
Peaks in May, Jun
Fascia, eaves, decks and untreated wood (carpenter bees); wall voids, trees (honey bees)
Spiders
Peaks in Jun, Jul, Aug, Sep
Basements, garages, corners, window frames, woodpiles
Termites
Peaks in Apr, May, Jun
Foundations, crawl spaces, wooden structures in contact with soil
Peak Active Low Dormant
[ 03 ] Climate
What Colorado's climate does to pest pressure
Mountain & West · zone 3b–7a
High-altitude semi-arid. Cold dry winters, hot dry summers, and huge elevation differences that change the pest list over short distances.
Dry, high-altitude conditions where elevation changes the pest list over short distances.
Seasonal timing moves with local weather. A warm wet spring in Colorado can pull a spring species forward by a month, and a dry year can delay a fall species. Use the bars above as a planning window, not a forecast.
[ 04 ] Local mistake
The thing homeowners in Colorado get wrong
A Colorado elevation change of a few thousand feet changes the pest list more than a change of state would. Front Range and the Eastern Plains are not the same climate and do not have the same insects.
[ 05 ] Prevention
What to do in Colorado before the season starts
Ordered by how much they move the needle in this climate, not by how easy they are.
- 1
Identify which elevation band you are in before following any seasonal calendar
- 2
Rodent-proofing matters more than insect control in most Colorado homes
- 3
Check for wasp nests in eaves and soffits in spring, before they become a removal problem
[ 06 ] Questions
Colorado pest questions
What is the most common pest in Colorado?
Flies, ants and mosquitoes are the three most-searched household pests in the United States. In Colorado the top-searched pest is Flies. It is a search-interest ranking rather than a count of infestations, but it tracks what people are actually asking for help with.
What month are pests most active in Colorado?
It depends on the pest, and the month-by-month answer differs by climate zone. Colorado sits mostly in USDA hardiness zone 3b–7a. Check the peak months on each pest card above, or use the full pest activity index for the year-long view. Seasonal timing always shifts with local weather, so treat the calendar as a planning aid rather than a forecast.
Can I treat pests in Colorado myself, or do I need a pro?
Most of the pests on this page are within reach of correct DIY if you identify the species first and use the method that matches it. Termites, bed bugs, wildlife in the attic and any infestation that spans several rooms are the honest exceptions. The pro threshold is usually about two weeks of correct method with no change, not about the size of the sighting.
Why do I get pests in Colorado even after treating?
In most repeat cases the treatment missed the source rather than failing. Water against the foundation, an unsealed gap that leads indoors, or a colony living inside a wall where a surface spray cannot reach it are the usual explanations. Identify where the pest is living before you buy anything for it.
Pro threshold
When to stop treating it yourself in Colorado
Two weeks of correct method with the right product and no change is the honest limit. Past that, a pro finds what you cannot see — and you should ask which product they are using and why, what the guarantee covers, and whether the price is per treatment or per year.
[ 07 ] Nearby
Other mountain & west states
Search-interest ranking: Organic Lesson, “The Most Troublesome Household Pests in Each State,” Google Trends analysis of 30 common household pests, reported by Pest Control Technology. Read the study summary. Zone ranges are USDA Plant Hardiness Zones. Monthly activity is this site's own dataset, also published on the pest activity index.