Common Backyard Pests in Denver (and How to Get Rid of Them)

Date Published: September 13, 2019

We’re not the only ones who enjoy Colorado’s warm and dry climate in the summer. Colorado has its share of bugs. Mosquitoes, bed bugs, Miller moths, and others that itch a ride on people, may be the most annoying, but others are even more destructive. It’s a huge problem when these pests decide to camp out around your house, yard and garden.

When inspecting your Denver home for problems like termites and mold, knowing which pests to look out for is crucial. Cockroaches, ants, and mosquitoes keep the exterminators busy, but beetles, girdlers, webworms, and billbugs are some of the most common backyard pests in Denver.

Scarab Beetles

scarab beetle


Scarab beetles are another name for June bugs. They fly near bright outdoor lights and in direct sunshine. June bugs start as fat white larvae, eating foliage, flowers and killing the grass. Dead patches of grass or damaged plants may mean there are ground-dwelling June bug larvae on the lawn. Natural insecticides such as neem oil and Bacillus Thuringiensis (Bt) are effective ways to control them. Bt is a type of bacteria that acts as a toxin against insects like caterpillars and beetles, but it won’t affect beneficial bugs in the yard and garden.

Cranberry Girdler

Cranberry girdlers look like something out of the movie “Alien.” They’re light-gray grubs with orange-brown heads.  These sod-loving webworms eat turf roots before ascending on trees. Girdlers chew on Kentucky bluegrass, bentgrass, and fine fescues that grow in Denver yards. Chemical pesticides such as trichlorfon (Dylox), clothianidin (Arena), or halofenozide (Mach 2) are effective treatments to control these invaders. But keep in mind, trichlorfon is toxic to people, birds, and fish, and is easily absorbed through the skin. Clothianidin isn’t toxic to humans, but it can pose a risk to honey bees and other beneficial insects.

Billbugs and White Grubs

White grubs and billbugs feed on the roots of turfgrasses and can attract skunks and other mammals that dig into the sod searching for food. White grubs eat the roots of your grass and usually live on the top few inches of soil.

The best way to control infestations of white grubs is to attack when eggs are beginning to hatch. Parasitic nematodes are useful for controlling billbug and white grubs. Keeping your lawn watered will also help keep these insects at bay.


Billbugs burrow down to grass stems and roots while they destroy turf crowns, especially in periods of drought in Denver. Billbugs are rather difficult to control because their hard bodies do not easily absorb pesticides. Kentucky bluegrass lawns are particularly susceptible to the larvae, and can spread from yard to yard.

Water and fertilizer may help to control infestations of billbugs and white grubs, especially before the grass enters dormancy in late summer. But if tunneling larvae kill grass plants before new blades have established roots, the young sod will die. Turf killed by billbugs must be reseeded.

Looking for a pest inspection to find wood destroying organisms and other insects that may be harmful to your current or future home? Learn more here.

Sod Webworms

These are moth-like insects that spin sleek webs in the grass and on foliage.  One of the most common backyard pests in Denver, webworms are gray or brown, and have dark spots on their backs.

Sod webworm larvae are about ¼ to an inch long and even though they’re living in the grass, they won’t do much damage to a healthy lawn. Organic fertilizers and lots of water will help keep infestations under control.

Other Common Backyard Pests in Denver


They’re not a major problem, but some Denver lawns may see minor damage from chinch bugs. Various kinds of mites — spider, clover, banks grass — are critters to watch for.  Mites settle in during hot and dry months, even in the winter, feeding on grass roots and blades. Leafhoppers are very common in Denver as well. The tiny insects are ecru to light-brown and they suck the sap from grass blades.

Water, Water, Water!

There are various types of organic and chemical pesticides to control common backyard pests in Denver. But one of the best ways to keep the bugs away is to water your lawn. Lawn mites hate water! Water also washes previously-applied insecticides into the soil and grass roots, as it pushes grubs to feed closer to the surface of the turf.  Dry turf encourages bugs to dig down deeper to find water — that’s where the serious damage occurs. If it’s not raining, water the lawn in the early morning so that it won’t dry up before reaching the roots.


Birds love to feast on worms, grubs, and other various insects. You can draw these feathered friends to the backyard with feeders and water baths. Make sure to put an agitator in the birdbath to avoid attracting mosquitoes! Before beckoning the birds, make sure there are no chemical insecticides on the lawn that will harm them.

This article was a guest post from John Williams. John Williams is an outdoor living expert and explorer. When he’s not traveling to nature’s most well-known beauty spots, he tends to the greenery surrounding his home.

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About the Author: Chris Scott

Chris Scott is an ASHI certified home inspector with multiple years of experience in home inspections, blower door testing, duct leakage testing, and Boulder Rental License Inspections. Chris is also the Website Coordinator for Scott Home Inspection.

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