A Mosquito Source Checklist for a Missouri Yard

Containers and saucers

Containers and saucers hold water for days after rain, and they are the sources most households can clear themselves. Empty, turn over or remove every one that holds water.

Walk the yard and the patio. Every plant saucer, bucket, pot dish, toy, tire and empty can that holds water is a source. Empty and turn it over, or move it under cover so rain cannot fill it. A saucer emptied once a week removes a breeding place that a treatment would otherwise have to cover.

Look inside the bottom of the bin lid, the folds of a tarp and the bottom of a wheelbarrow. Those are easy to miss and they hold water.

• Plant saucers emptied or removed
• Buckets, tires and cans turned over or covered
• Tarp folds and wheelbarrows drained
• Pet water bowls changed every day

Gutters and downspouts

A gutter that holds leaves holds water, and a downspout that discharges into a low bed creates a standing pool. Clear the gutters and check the discharge.

Clear the gutters of leaves and debris at least twice a year, and more often under trees. Check that each downspout carries water away from the house and does not discharge into a low bed where it stands. A splash block that tilts toward the bed is a common cause.

Note any gutter that holds water after a dry day. A sagging section, a blocked outlet or a joint that leaks is a source, and it is recorded for repair.

• Gutters cleared of leaves at least twice a year
• Downspouts discharging away from the house
• Sagging or blocked sections noted for repair

Ponds, birdbaths and pools

Larger water is treated differently. A birdbath is changed and scrubbed, a pond is treated at its margins by the technician, and a pool cover is drained of rainwater before it is removed.

A birdbath should be changed every few days, and it should be scrubbed to remove the eggs. A pond is a different case: the technician treats the margins and the shaded planting beside it, and the household does not drain or treat the water itself without advice.

A pool cover that holds rainwater is a source. Pump it off or fold the cover so the water runs off, and tell the technician about any pool or pond on the property before the visit.

Resting shade

Adult mosquitoes rest in the shade during the day. The dense planting, the underside of the deck, the shed and the corner behind the shrubs are where they wait, and the technician treats those places.

Walk the planting that touches the house or the fence, and look under the deck, behind the shed and in the dense corners of the yard. Trim the planting where it is thick enough to shelter insects, and note the places the technician should look at on the day.

A shaded lawn that stays damp is another resting place. Improve the drainage where a low corner holds water, or note it for the technician to inspect.

• Dense planting touching the house or fence trimmed or noted
• Underside of the deck and the shed checked
• Damp shaded corners noted for drainage or treatment

What the technician treats and what it leaves

The technician treats the sources that cannot be removed and the places where the adults rest. The household is told which sources are its own to change, and which are outside the property.

A source that cannot be removed, such as a ditch, a field edge or a neighbor's pond, is recorded and not treated by the household. The technician treats the margins that are reachable and says which places are outside the property.

The follow-up is timed after rain. The record shows which sources were removed, which were treated and which remain, so the household can see what has changed between visits.

Gutters that hold water after a dry week

A gutter that still holds water several days after rain is a breeding site, and the cause is usually a sag, a blocked outlet or a joint that has opened. Finding the reason matters more than emptying the gutter once.

Run a hand along the gutter after a dry spell and look for a low point where the water sits. A section that sags between brackets will hold a pool no matter how often it is cleared. Check the outlet at the downspout, since leaves or grit packed into the elbow turn a working gutter into a reservoir. A seam that has separated lets water out at the joint and often hides the damage behind the trim.

Write down the spot and the cause. The fix may be simple, such as re-pitching a bracket or cleaning an elbow, or it may be a repair the owner schedules. The record lets the technician see whether a source reappears after the repair.

Planters, pot feet and the saucer that holds more than it should

Potted plants create hidden water: the saucer beneath, the pot feet that lift a container and leave a film of water and the drainage hole that a root has blocked. Each is cheap to fix and easy to overlook.

Tip every pot once a week during the warm months and pour off what has collected. Set pots on feet or gravel so the base is not sitting in water. Where a pot has no drainage hole, it is a container with a permanent source, and the owner should either drill it or remove it from the patio.

Bird feeders and the trays under them also collect water and seed. A tray that is cleaned weekly is a small job, and one that is left alone can become a larger source than any saucer on the property.

Shaded planting, the deck and the shed

Adult mosquitoes leave the open lawn in daylight and wait in cool, dense shade. The underside of a deck, a thick hedge, the north side of a shed and a bed of broad-leaved plants are typical resting places.

Walk those places at midday and note where the air is still and the ground is damp. Trimming a hedge so light and air move through it reduces the shade without removing the plant. Lifting skirting around a deck to let air under it does the same for the space beneath. These changes make the site less attractive to adults that would otherwise rest there.

The technician treats the resting places on the scope that the owner agrees to, and the trimming decisions are the owner's. A plant the owner does not want cut can still be left in place, with the shade it creates recorded on the scope as a resting site.

Ponds, creek margins and the water the owner cannot move

Some breeding water cannot be emptied, and the owner's job there is to report it and let the technician treat the margin rather than the open water.

A pond with still water, a ditch that holds a line of standing pools or a creek bank with backwater is outside a household's power to drain. The owner should note where it is, how large it is and whether it sits on the property or beyond the boundary. The technician then decides what can be treated at the margin and says which parts the owner would need to raise with a neighbor or a land manager.

A household should not drain a pond or a ditch it does not own, and should not apply a product to the water without advice. Those steps can damage wildlife and neighboring land, and the technician keeps to the margins for that reason.

Keeping the list for the next visit

A yard checklist is only useful if it is kept. The owner keeps a dated list of what was emptied, cleared, trimmed or reported, and the technician compares it with the scope at the next return.

Pin the list where the household will see it, such as on the garage door or inside a cupboard, and add a date each time a source is cleared. The return visit then starts from the owner's own record, which speeds the walk and shows what has or has not been done.

If a source keeps returning, the list shows the pattern. A saucer that fills every week after rain points to a yard with poor drainage, and the technician can then recommend a change to the grade rather than another round of treatment.