Missouri Pest Control Calendar: What to Treat Each Season

Central Missouri's four distinct seasons create predictable waves of pest activity throughout the year. Knowing what to expect and when to act puts you in a proactive position — treating before populations peak rather than reacting after they have established. Here is a practical seasonal guide for Franklin, Gasconade, and surrounding county homeowners.

January – February: Winter Monitoring and Early Preparation

• Active pests: Rodents inside structures; overwintering stink bugs, boxelder bugs, and lady beetles occasionally active on warm days inside walls and attics
• Treatment focus: Monitor rodent bait stations and traps; seal any additional entry points discovered during winter; plan spring exclusion work
• Best action: Schedule a late-winter perimeter treatment (February) to establish residual before spring insects activate — this early treatment is one of the most cost-effective investments in the pest control calendar

March – April: Spring Emergence

• Active pests: Overwintered ants activate (odorous house ants, pavement ants); termite swarmers emerge March–May; spiders become active; stink bugs and boxelder bugs exit overwintering sites and move outside
• Treatment focus: Spring perimeter treatment; termite inspection; ant perimeter and bait program begins
• Best action: If you haven't had a termite inspection in more than a year, schedule one in March or April when swarmers are most visible — finding swarmers inside is the most common first sign of an active termite infestation

May – June: Peak Activity Season Begins

• Active pests: All ant species at peak activity; mosquitoes and ticks become significant; cockroach activity increases; spiders building webs and egg sacs outdoors
• Treatment focus: Start mosquito/tick yard program; maintain ant perimeter treatment; summer general pest perimeter treatment
• Best action: First mosquito treatment of the season in early May before populations build — treatment is more effective at lower population densities

July – August: Summer Peak

• Active pests: Peak mosquito season; ticks remain active; ant populations at maximum; German cockroach reproduction peaks in warm kitchens; brown recluse spiders active at night
• Treatment focus: Maintain mosquito/tick treatment cycle (every 3–4 weeks); summer perimeter treatment; address any cockroach activity promptly — populations build fastest in hot weather
• Best action: Inspect for brown recluse activity in crawlspaces and basements — summer is when populations are most visible and most active

September – October: Fall Transition

• Active pests: Stink bugs and boxelder bugs begin fall invasion; mice begin entering structures; spiders at peak visibility outdoors; mosquitoes still active through September; tick activity continues
• Treatment focus: Fall perimeter treatment (the most important treatment of the year for exclusion value); rodent exclusion and bait station deployment; last mosquito treatment of season
• Best action: Schedule fall perimeter treatment in mid-September — this is the prime window to address stink bugs, boxelder bugs, and mice simultaneously before the peak invasion period

November – December: Closing the Season

• Active pests: Indoor rodents (mice active year-round inside heated structures); overwintering insects in wall voids becoming active on warm days
• Treatment focus: Rodent monitoring and control; assess exclusion work completed before winter; final perimeter treatment if not done in October
• Best action: Confirm rodent control is in place before the holiday season — increased food activity and visitors mean more opportunities for introduced rodents and more impact from an uncontrolled population

Year-Round: What Never Stops

• German cockroach control — they reproduce year-round in heated structures and infestations do not follow seasonal patterns
• Brown recluse management — present and active in heated structures year-round
• Rodent monitoring — mice inside heated homes are active 365 days a year
• Termite inspection — active termite colonies work year-round, though swarming is seasonal