Mosquitoes

In summer the whole cycle takes a week or less, depending on water temperature. That is the reason the standard advice is to change bird bath and pet bowl water weekly rather than occasionally. You are beating the clock, not tidying up.

Two features separate a mosquito

Small, delicate, two-winged flies. Two features separate a mosquito from the things it gets mistaken for. The first is the long slender proboscis, the tube it uses to pierce skin. The second needs a magnifying glass: small scales cover the wings, which no similar fly has.

Crane flies get blamed

They do not deserve it. They are much larger, and despite the nickname mosquito hawk, they do not eat mosquitoes. Non-biting midges are the other common mix-up.

Only females bite

There is a physical reason. Males feed on nectar and fruit juice, and the CDC notes the male proboscis is not strong enough to pierce skin at all. Females need blood only to develop eggs.

The larvae tell you the genus

In the water, the larvae tell you the genus. Culex and Aedes larvae have a distinct air tube at the tail end. Anopheles larvae do not.

Look for the larvae, not the adults

By the time you are being bitten, the nursery has already produced. Wigglers hang just beneath the surface of anything holding still water, and comma-shaped pupae tumble alongside them.

Run the container list

Bird baths, buckets, plant pot saucers, old tires, soda cans, tree holes, rain barrels, clogged roof gutters, street gutters and catch basins, cooler drains, watering troughs, plastic pools, septic openings, and any pool or spa that has stopped being maintained.

The threshold is lower than people expect

UC IPM's own example is that even a bottle cap holding water can support larvae. This is why a yard inspection takes as long as it does.

One clean-out is not enough, and here is why

Container-breeding Aedes lay eggs just above the waterline. Those eggs survive drying for months, and they do not all hatch the first time they are flooded. Every rain re-seeds the site.

The strategy follows the biology

The whole strategy follows from the biology: three of the four stages are in water, so larval control is what works and adult spraying is the weakest link, not the strongest.

Weekly beats occasional

Change the water in bird baths, pet dishes and watering troughs every week, which beats the egg-to-adult clock. Empty and turn over unused containers. Fill tree holes with sand or mortar. Clean gutters and downspouts. Do not overwater the landscape.

Rain barrels are forgotten

Rain barrels are the source people forget. Screen or seal every access point, keep the filters and pre-filters clear, and check regularly for cracks, leaks and failed seals around the valves.

Bti works, with one limit

Bti works, with one honest limit. Bacillus thuringiensis israelensis is a bacterium that kills mosquito larvae and leaves people, pets and plants alone. Mosquito Dunks last about 30 days. But larvae have to eat it, and pupae do not feed, so any pupae already present will still become adults. That is why a treated barrel can keep producing for a couple of days.

Repellents, with the numbers

These are the numbers that matter. DEET and picaridin are the conventional choices. Oil of lemon eucalyptus, its synthetic form PMD, and IR3535 are the CDC-recommended alternatives, though PMD is not for children under three. Protection typically lasts four hours or less. Higher concentrations last longer, but above 50 percent there is no meaningful gain, and under 10 percent you may get only an hour or two. Permethrin treats clothing and must never go on skin.

What does not work

Most of it is sold anyway. Repellent wristbands, ultrasonic emitters, electric grids, electronic repellers, the so-called mosquito plant, incense coils, vitamin B1, and brewer's yeast and garlic mixtures. Citronella candles and coils only help outdoors with very little air movement.

Bug zappers are worse than nothing

Bug zappers are worse than doing nothing. UC IPM calls them counterproductive, because many of the insects they kill are the ones that prey on mosquitoes.

Call your vector control district

Call your county mosquito and vector control district first. They exist in most of the country, they are free, and they do larval surveillance and disease testing that no private company duplicates. Then treat the yard. Two honest limits on what any yard work can achieve: adults fly several miles from where they hatched, so your neighbors' water matters as much as yours, and outdoor sprays reduce adults only temporarily with no lasting effect. That is worth knowing before you pay for one.