Common garden bugs in Colorado and how to get rid of them

Pests in the home garden are aplenty this year. We had a wet spring and a hotter-than-hot early summer. Areas are under continued drought conditions and we have erratic weather patterns from climate change. All of that equals the perfect storm for garden pests.

The list of insects we find in our gardens along the Front Range Corridor is long. Everyone has his or her own hierarchy of most- to least-despised insects. The debates often depend on what damage they do to a garden’s most prized possession.

Here’s a look at some of what’s showing up as we move into late summer.


If you’ve lived in Colorado for a hot minute, you know about our abundance of grasshoppers, in many sizes and colors. They’re worse with drought conditions, as they lay more eggs.

Grasshoppers are most frustrating for gardeners. They love leafy vegetables and are highly migratory, making control near impossible if your neighbors don’t all take the same steps.

With most grasshoppers at adult stage right now, controls are limited. Folks in online gardening forums recommend a good chop in half with gardening shears — which is not for the faint of heart. To read more on control attempts of Colorado’s hoppers at the Colorado State University Extension Service.

Japanese beetles 

Japanese beetles have increased in force over the Front Range only over the last few decades, even though they were introduced into the United States in 1916. They lack a natural predator, so you must become the predator, by picking off each and every one you see.

These beetles start out as those fat, creepy, white grubs burrowed in lawns and gardens. They emerge as metallic green beetles — almost pretty if you didn’t know their destructive potential. They are damaging at both larvae and adult stages. The larvae eat grassroots, while the adults eat everything above ground. They are known for “skeletonizing” leaves; that is, eating the softer greenery around the veins.

Denver Post gardening columnist Betty Cahill did a thorough story on the nasty beetles in 2020, if you want to know more.


Brush by my leafy plants right now (the cukes and squashes) and a flurry of tiny whiteflies scatter.  They are super common sap-sucking flies that love indoor and outdoor plants alike. Luckily, the outside ones freeze in our winters. So if your outside plants suffer from them now, know they won’t last. But infestation is an issue if these get into your indoor plants, where they can live year-round.


Fat, squishy hornworms have been known to cause squeamish responses. Yet they turn into sphinx moths (also known as hummingbird moths). Most common here are tobacco or tomato hornworms. All varieties can be picked off of plants at the caterpillar stage.

However, the caterpillars are good pollinators, thus creating a dilemma. Caterpillars can be fun for kids — OK, anyone — to raise and release. You can also check your local butterfly center to see if they will rehome them. Go to the CSU Extension Service to find out more about the varieties of hornworms that we have in Colorado.

Cabbage butterflies 

Cabbage butterflies are often confused with similar cabbage moths that are more gray and lack the black dot on the wings. Both enjoy snacking on similar garden veggies as caterpillars. If you’re seeing them now flying around, get ready to hand-pick them off as eggs and caterpillars.

Beneficial insects

A healthy ecosystem invites predators. A garden full of praying mantis, ladybugs, lacewings and assassins can do some good work on aphids and eggs of other pests. Be sure to learn the difference with ladybug and lacewing larvae, as they eat aphids. Often these larvae get confused as pests when they can actually demolish large amounts of aphids.

Support host plants for parasitic wasps. They feed on nectar, so try yarrow or dill and other enticing flowers. These are quite opposite of predatory wasps like Yellowjackets. Parasitic wasps inject their eggs into specific hosts like Japanese beetle larvae. They don’t sting people or mess with bee populations. When spraying insecticides, often these beneficial insects get hit as well. This can escalate the pest situation rather than remedy it.


Good pest management is about prevention, maintenance and healthy ecosystems.

Insecticides are available for some of these insects. However, I’m not an advocate of th em. Beneficial bug friends can be damaged depending on what’s used and how it’s applied. Soil organisms are affected. Accumulation occurs over time. Birds eat the sprayed bugs. And the cycle goes on.

Start planning for next summer. Design your garden for pest management. Spread out plants that commonly attract the pests in your yard, knowing that every yard or growing area is a mini-ecosystem with its own needs. Avoid planting all the tomatoes in the same area, for example. Employ a polyculture approach.

Add a row cover or netting, especially over newer or more tender plants. This can deter flying insects some. Row covers can also help keep beneficial insects in more, like if you’ve installed some ladybugs from the gardening store.

Simple picking off and smushing of bad pests works great. Get some kids to handpick beetles and grasshoppers. Drop beetles in a bucket of soapy water so they don’t escape. Check the underside of leaves and smush any eggs found.

Nighttime hunting can be fun. Put on your headlamp and pick slugs by following their slimy, shimmery trail.

If the situation gets bad, consider organic controls like soapy water or neem oil. These work well on eggs and larvae stages or aphids. Insects with soft outer bodies get smothered by applying these. Always apply at night after other pollinators and insects have gone to bed. For more instructions of safe use of oils and soaps, check out these Colorado Master Gardener resources:

Insect Control: Horticultural Oils – 5.569

Insect Control: Soaps and Detergents – 5.547

Of course, this is only a small sampling of what’s hitting our gardens right now. Here’s a shout-out to the slugs, earwigs, ants and predatory wasps, to name a few other pests. We see you, but our attention is on other creepy crawlies right now.

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