Fall is the time to kill next year's mosquitoes

Mosquitoes overwinter in different ways depending on species, but targeting them in late fall is the single most effective thing you can do to reduce spring populations.

The ones that annoy you in summer — Aedes (floodwater mosquitoes) and Culex (house mosquitoes) — each have a different survival strategy. Aedes lay eggs in damp soil or containers, and those eggs can survive winter and hatch when snowmelt or rain floods them. Culex females find a protected spot like a hollow log, a storm drain, or your basement and go dormant as adults. A few species even overwinter as larvae in ice-covered ponds.

So here’s the late-fall game plan:

1. Kill the adults that are fattening up. Before the first hard freeze, female Culex are filling up on sugar (plant nectar) to get through winter. If you set out a CO₂ trap or residual spray in late October (depending on your zone), you can knock them out before they go dormant. This is your best bang for the buck.

2. Drain everything. Those Aedes eggs are microscopic and can sit for months. Tip over plant saucers, flush bird baths weekly, dump kiddie pools. Get water out of anything that holds it. This doesn’t kill the eggs already laid — but it prevents more from being laid before frost.

3. Treat water you can’t drain. If you have a rain barrel or a pond, drop a Bacillus thuringiensis israelensis (B