The PA ant calendar
- February: Colonies are dormant inside warm wall voids. No visible activity. Not the time to spray.
- March–early April: Workers emerge with the first 50°F+ days. Spring "swarms" of winged carpenter ants happen now. Best window for pre-emptive treatment.
- April–May: Trails establish. Sugar-feeding ants (odorous, pavement) become highly visible in kitchens.
- June–August: Activity peaks. Carpenter ant secondary colonies form in nearby trees and outbuildings.
- September–October: Workers start storing food for winter. Last chance to bait before activity drops.
- November–February: Mostly dormant. Treatment effectiveness drops because foragers are inactive.
Why pre-emptive (March) wins
When you treat in March, the colony is at its smallest. Non-repellent bait that gets back to the queen at this stage can wipe out the colony before it has the chance to send out hundreds of foragers. By July, the colony is 10x larger and requires more bait and more visits.
What you can do yourself in late February
- Walk the foundation. Look for gaps larger than a pencil-eraser around utility lines.
- Clear leaves from foundation beds. Damp leaves are carpenter ant condos.
- Pull mulch 12 inches back from siding.
- Trim shrubs touching the house — ant superhighways.
Combined with a pro spring treatment, this keeps most homes ant-free through the entire season.