Key Takeaways
- Pest activity in Iowa changes with the seasons—knowing when they peak helps with proactive prevention.
- Winter pests like rodents and spiders seek warmth and shelter inside homes.
- Spring brings increased ant and termite activity, especially during wet, warming months.
- Summer is peak infestation season, with mosquitoes, wasps, ants, and ticks thriving outdoors and indoors.
- Fall triggers pests to migrate indoors, especially boxelder bugs, Asian lady beetles, and rodents.
- Weather plays a major role—mild winters and rainy springs can extend or intensify pest seasons.
- Year-round pest control is the most effective way to stay protected no matter what Iowa’s climate throws at you.
Living in Iowa means getting a front-row seat to all four seasons—and unfortunately, so do the pests. From freezing winters to humid summers, each shift in weather brings a new lineup of unwelcome guests trying to invade your space.
Whether it’s ants in the pantry, wasps near the deck, or mice in the basement, knowing when pests peak is half the battle. That’s why we’ve put together this month-by-month breakdown of Iowa’s most active pest seasons—so you can stay one step ahead all year long.
Let’s break it down by season, pest by pest.
Winter (December – February): Dormant, But Not Gone
While most pests slow down in the cold, that doesn’t mean they disappear. In fact, some of the worst offenders are just getting comfortable—inside your home.
🔍 Common Winter Pests:
- Rodents (mice, rats) – seeking warmth, nesting in attics, basements, and wall voids.
- Spiders – especially cellar spiders and house spiders.
- Cockroaches – resilient and still active in warm, humid areas like kitchens and laundry rooms.
Janssen Tip:
This is the season for sealing cracks, checking vents and pipes, and storing food in airtight containers. If you hear scratching in the walls or see droppings, it’s time to act.
Winter isn’t quiet—it just moves indoors.
Spring (March – May): Waking Up and Moving In
As the snow melts and the soil warms, pests come alive. Spring in Iowa kicks off the official start of pest season.
🌱 Common Spring Pests:
- Ants – particularly odorous house ants, start scouting for food.
- Termites – swarmers emerge in April and May.
- Wasps – begin building new nests around eaves, decks, and garages.
Rain + warmth = moisture problems. Moisture attracts everything from ants to termites. Now’s the time to inspect your foundation, clean gutters, and stay ahead of the curve.
Janssen Tip:
Schedule a spring pest inspection to catch any colonies before they get comfortable.
Spring is when pests make their comeback. Be ready.
Summer (June – August): Peak Infestation Season
Welcome to prime pest time.
The heat kicks activity into high gear, especially for outdoor pests like mosquitoes, fleas, and wasps. You’ll also see an uptick in ants, spiders, and other household invaders making moves indoors to beat the heat.
☀️ Common Summer Pests:
- Mosquitoes – thriving near standing water and shaded areas.
- Wasps & hornets – defending nests aggressively.
- Ants – expanding colonies and invading kitchens.
- Fleas & ticks – common in yards, especially if you have pets.
- Earwigs & millipedes – moisture-loving pests that sneak into basements and bathrooms.
Janssen Tip:
Eliminate standing water, keep yards trimmed, and inspect play equipment, grills, and patio furniture for nests.
Summer is beautiful—but pests think your backyard is theirs.
Fall (September – November): The Great Indoors Migration
As temperatures dip, pests make a mad dash for warmer environments—and your home is at the top of their list.
🍂 Common Fall Pests:
- Boxelder bugs
- Asian lady beetles
- Spiders
- Mice and rats
These invaders often show up suddenly—on walls, windows, or creeping along the floor. They’re not just annoying—they’re looking to hunker down for winter.
Janssen Tip:
Fall is the perfect time for a perimeter spray and full-home sealing. Don’t give pests a head start on winter.
If you see one bug on your wall in October, dozens more may already be inside.
Iowa’s Wildcards: Weather-Driven Surprises
Here’s the kicker: Iowa’s weather can throw pest patterns into chaos.
- Warm winters can keep insects active well into December.
- Wet springs lead to mosquito surges and termite blooms.
- Early falls can push pests indoors sooner than expected.
That’s why rigid schedules don’t always cut it. The key is to stay flexible—and proactive.
Janssen Tip:
If you’re unsure, or things feel “off,” call us. We’ll assess what’s happening right now, not just what the calendar says.
Conclusion: The Calendar is Your First Line of Defense
Pests don’t follow rules—but they do follow patterns. Knowing when they’re likely to strike gives you the upper hand.
The best way to protect your home? Pair seasonal awareness with professional help. Janssen offers year-round pest protection plans built for Iowa’s wild seasons and unpredictable weather.
Your home is your castle. We’ll help you guard it.
📅 Ready to take control?
Book a free home assessment and let’s build a pest-free plan that fits your lifestyle.
Frequently Asked Questions (FAQ)
1. What are the worst months for pests in Iowa?
The most active pest months are typically June through August, when ants, mosquitoes, wasps, and other insects are most aggressive. However, April–May and September–October are also key transition months when pests emerge or begin moving indoors.
2. Why do I still see pests in winter?
Even in freezing temperatures, indoor pests like mice, spiders, and cockroaches remain active. They seek warmth, food, and shelter inside homes, especially in basements, kitchens, and attics.
3. When should I schedule pest control in Des Moines?
The best approach is seasonal or year-round prevention. Spring and fall are ideal for inspections and barrier treatments, but if you’ve already noticed signs of pests, it’s never too early—or too late—to call.
4. How does Iowa’s weather affect pest patterns?
Iowa’s variable climate means pest seasons can start earlier, last longer, or intensify depending on temperature and rainfall. For example, a warm winter might keep ants and spiders active, while a wet spring can lead to a mosquito boom.
5. What pests should I watch for each season?
- Winter: Rodents, spiders, cockroaches
- Spring: Ants, termites, wasps
- Summer: Mosquitoes, fleas, ticks, ants, wasps
Fall: Boxelder bugs, Asian lady beetles, mice, spiders