Bugs and artificial turf: mosquitoes need standing water, ants need a way in

01Can mosquitoes breed in artificial turf?

Only in water that stays on it. Culex mosquitoes lay floating rafts of 100 to 300 eggs on standing water, including small containers such as buckets, toys, birdbaths and flowerpots, and an egg needs 7 to 10 days to become a flying adult. Water that drains the day after a storm can’t raise a generation; a puddle that lasts a week can. That is why Larimer County asks residents to drain standing water in their yards at least once a week (Larimer County).

Where water lingers in a turf yard:

• A dip over slow clay. Longmont warns that its “clay soils absorb water slowly” (City of Longmont), and in Greeley the water department finds hard clay “sometimes just inches below the surface” (City of Greeley). A low spot with nowhere to send its water holds a puddle for days. See why water puddles on turf and turf that’s sinking or uneven.
• A backing that no longer drains. Leaves left over winter can rot into “a layer of organic matter that can impede drainage,” FieldTurf’s landscape guide warns (FieldTurf Landscape). See clearing leaves off turf.
• A putting green. Putting green turf commonly has a backing that lets no water through, Synthetic Grass Warehouse says (SGW), so rain leaves only by running off the contours. See putting green maintenance.
• A leaking cap. Sprinkler heads capped under turf “may leak over time,” SGW’s installer guidance warns (SGW), and Larimer County’s mosquito list asks homeowners to repair broken sprinkler heads (Larimer County). More in what happens to the sprinkler system.
• Things left on the turf. Once a week, CDC says, empty and scrub, turn over, cover or throw out toys, pools, birdbaths and flowerpot saucers (CDC). Longmont adds clogged gutters and kiddie pools to the usual breeding sites (City of Longmont).

Resting adults find little shelter on turf. CDC says Culex rest “in grass, shrubs, and other thick vegetation where it is cool, dark, and humid,” and Larimer County asks that tall grasses be cut. Turf stays short; the shrub bed beside it and the shade under the patio chairs don’t. Nor does a dry yard stop mosquitoes flying in: CDC says Culex have been known to fly up to 2 miles, and CSU Extension says adults typically fly “a mile or two to feed” (CSU Extension). Draining your yard cuts what hatches there, not what the neighborhood raises.

02How much West Nile virus is in Northern Colorado this year?

Some every summer. Larimer County says the virus “is likely already circulating in local mosquito populations, as it does every summer,” and has found infected mosquitoes every year since 2003, when Colorado’s largest outbreak brought over 2,800 reported cases and 63 deaths.

Weld’s trapping zones take in Greeley and Evans, Johnstown and Milliken, and Firestone and Dacono. Culex bite most from dusk to dawn, and CSU says the West Nile carriers peak in July and August: midsummer evenings on the patio are when Larimer County’s advice to wear an EPA-registered repellent counts. Its dashboard draws a 1-mile circle around every trap that tests positive, so you can see whether your address falls inside one.

Spraying is up to towns. Larimer County has no mosquito program of its own; towns such as Windsor, Timnath, Loveland and Fort Collins pay the contractor VDCI, and the county asks residents to report standing water to their town. Longmont contracts VDCI too.

03Why are ants nesting under my turf?

Because they were there first. “Tremendous numbers of ants normally reside in a typical house lot,” CSU Extension says, mostly underground where nobody notices (CSU Extension). Pavement ants nest under pavement or rocks and pile small mounds of soil at the entrances; field ants nest in loose soil. Turf over a compacted rock base covers a colony much as a paver does, and the ants still need a way up. On turf that shows as a little pile of sand or fine soil at a seam, an edge or a drain hole, and the holes stay open because water and air pass through them.

CSU calls ants “quite beneficial” overall; many eat other insects. When a colony is a nuisance, such as mounds on the putting line, CSU’s advice works on turf too:

• Bait, don’t spray. Insecticide on a nest often kills only the ants on the surface, and a disturbed colony opens new entrances elsewhere. Baits, which workers carry inside, “will usually provide the most satisfactory control,” with results in a week or two.
• Keep baits fresh. They “often become unattractive when they dry out, a common problem in the arid climate of Colorado,” so check them often in a sunny yard.
• Leave the kettle inside. CSU says boiling water carries more hazard than ant insecticides, with less chance of working.
• Read the label for when kids and pets can go back on the turf; CSU reminds readers that following it is the applicator’s job.
• Take away food and cover. Rinse spills the same day, and keep heavy mulch and leaf piles off the foundation, where CSU says they can shelter a colony.

04Can fleas or ticks live in artificial turf?

They can cross it, but neither makes a home in it.

Fleas come in on animals. CSU says fleas “are rarely problematic” given Colorado’s dry climate, because cat flea eggs need more than 50% relative humidity to hatch (CSU), and the Colorado Climate Center calls the state’s humidity “generally quite low” (Colorado Climate Center). Larvae stay near the host’s bedding or nest, away from light. If the dog has fleas, check its bed, the doghouse and any den under a deck or shed; CSU links the human flea most often with skunks, foxes and coyotes. Near a prairie dog colony, Colorado Parks and Wildlife asks pet owners to use flea preventatives, because prairie dog fleas can carry plague (CPW).

Ticks wait on plants. CSU Extension says hard ticks climb onto vegetation and hold still until a passing animal brushes them, gathering along “brushy areas along the edges of fields and woodlands or commonly traveled paths through grassy areas and shrublands” (CSU Extension). They are most common at higher elevations and most active in spring and early summer. Short turf gives a tick nothing to climb; a strip of native grass or brush where a lot backs onto open space does. The exception is the brown dog tick, which develops only on dogs and turns up where dogs are kept together, such as kennels; see artificial turf for dog daycares.

05What should I check each week to keep bugs down?

From June through early September, when Weld County says its mosquitoes are most active (Weld County):

1. Walk the turf the day after a storm. Water still standing is a drainage problem; see why water puddles on turf.
2. Empty anything that holds water: saucers, toys, wading pools, pet bowls. Larimer County says to change birdbath water at least weekly, twice a week in hot weather.
3. Keep leaves and cottonwood fluff off so the backing keeps draining.
4. Look for a wet spot in a dry week. It can mean a leaking line or cap under the turf.
5. Pick up after the dog and rinse the spot. CSU says blow flies commonly breed in pet waste (CSU Extension); more in dog poop on artificial turf.
6. Scan seams and edges for little piles of sand, the sign of an ant entrance.

Two questions for whoever builds or repairs the turf: where does water leave the base on this lot, and was the old lawn zone shut off at the valve? A good answer names a place lower than the turf, such as an edge, a bed or a drain, and says the zone was turned off at the valve instead of capped under the turf. More in questions to ask a turf installer, and for dog yards on the pet turf page.