Mosquitoes in an Arizona yard — source reduction beats spraying, every time.

The standing-water hunt

Some species breed in a container the size of a bottle cap, and a week is enough.

• Plant saucers, buckets, and wheelbarrows — dump anything holding water after every storm.
• Irrigation and valve boxes that hold water after a cycle.
• Blocked roof drains, scuppers, and low spots in the yard that never dry.
• Pet water bowls, bird baths, and fountain basins — refresh every one to two days.
• Pool covers with pooled water on top, and any neglected green pool nearby.
• Tires, tarps, boat covers, trash can lids, and the tray under the AC condensate line.

Water you cannot drain

• Bti dunks and granules — a bacterial larvicide sold for standing water — target mosquito larvae without harming birds, pets, or fish when used per label.
• Ponds and stock tanks: mosquitofish or a properly circulating pump usually solve it, since mosquitoes need still water.
• Fountains and water features: keep the pump running, and treat the basin if flow stops.
• Pools: a functioning, circulating, chemically balanced pool does not breed mosquitoes. An abandoned green pool is a neighborhood-scale source.
• Report a persistent green pool or standing water on a vacant property to your county's environmental services department — that is what they are for.

Reduce the resting habitat

• Adults rest through the day in cool, humid, shaded vegetation — dense ground cover, thick ivy walls, and unpruned shrub interiors.
• Thinning the interior of dense shrubs and keeping ground cover off the soil surface removes daytime shelter.
• Fix irrigation overspray that keeps a shaded corner permanently damp.
• Improve drainage in the shaded side yard nobody uses; it is often the source of everything.
• Keep the yard's grade moving water out after monsoon storms rather than holding it in low spots.

What helps on the patio tonight

• Moving air. A patio fan is remarkably effective — mosquitoes are weak fliers.
• Screens and mesh panels on a ramada or patio enclosure.
• EPA-registered repellents on skin for the people who are sitting outside.
• Citronella plants do essentially nothing standing in a pot; the oil must be released to have any effect, and even then it is short-range.
• Bug zappers kill mostly harmless insects and are ineffective against mosquitoes.

Why we do not recommend routine yard fogging

• It kills adults present at that moment and offers little residual protection against the next hatch.
• It also kills bees, butterflies, lacewings, ladybugs, and the predators that help control other pests.
• It does not touch the breeding source, so the treatment becomes a subscription.
• Repeated broad-spectrum use contributes to resistance.
• The same money spent on drainage correction fixes the problem permanently.