There are plenty of pests in the home garden this year. We had a wet spring and a hotter than hot early summer. Areas are under persistent drought conditions and we have erratic weather patterns due to climate change. All of this equates to the perfect storm for garden pests.
The list of insects we find in our gardens along the Front Range Corridor is long. Everyone has their own hierarchy of the least despised insects. The debates often depend on the damage they do to a garden’s most valuable property.
Here’s a look at some of the things that show up in late summer.
Whitney Cranshaw, Colorado State University, Bugwood.org
Locusts
If you’ve lived a hot minute in Colorado, you’ll know our abundance of grasshoppers in many sizes and colors. When it is dry, they are worse because they lay more eggs.
Grasshoppers are the most frustrating for gardeners. They love leafy greens and are very migratory, making it nearly impossible to control unless your neighbors all take the same steps.
For most adult locusts, controls are currently limited. People on online gardening forums recommend chopping up a good half with secateurs – which is not for the faint of heart. Read more about Colorado State University Extension Service control attempts on Colorado’s hoppers.
Japanese beetles devour a flower in late August. (Provided by Betty Cahill)
Japanese beetles
Japanese beetles have only gained strength in the Front Range in the last few decades, although they were introduced to the United States in 1916. They lack a natural predator, so you have to become the predator by seeing each one you choose to take down.
These bugs start out as those fat, creepy, white maggots buried in lawns and gardens. They appear as metallic green beetles – almost pretty if you weren’t aware of their destructive potential. They are harmful in both the larval and adult stages. The larvae eat grass roots, while the adults eat anything above ground. They are known to “skeletonize” leaves. that is, to eat the softer green around the veins.
The Denver Post’s gardening columnist Betty Cahill made an in-depth story about the nasty bugs in 2020 if you want to know more.
Whiteflies on the underside of a cucumber leaf. (Tamara Yakaboski, Denver Post Special)
Whiteflies
Now brush through my foliage plants (the cukes and pumpkins) and a flood of tiny white flies is scattering. They are very common sap-sucking flies that love indoor and outdoor plants alike. Fortunately, the outer ones freeze in our winters. If your outdoor plants suffer now, you know they won’t last long. But infestation is a problem if these get into your houseplants, where they can live year round.
Hornworms
Fat, squishy hornworms are known to cause squeamish reactions. Nevertheless, they transform into sphinx moths (also known as hummingbird moths). The most common here are tobacco or tomato hornworms. All varieties can be picked from plants at the caterpillar stage.
However, the caterpillars are good pollinators, which creates a dilemma. Caterpillars can be fun for kids – OK, anyone – to raise and release them. You can also check your local butterfly center to see if they are taking them back in. Visit the CSU Extension Service to learn more about the types of hornworm we have in Colorado.
A cabbage butterfly on a Rocky Mountain Bee plant. (Tamara Yakaboski, Denver Post Special)
Cabbage butterflies
Cabbage butterflies are often confused with similar cabbage moths, which are grayer and lack the black dot on their wings. Both enjoy snacking on similar garden vegetables such as caterpillars. If you see them flying around now, get ready to hand-pick them as eggs and caterpillars.
Useful insects
A healthy ecosystem invites predators. A garden full of praying mantises, ladybugs, lacewings, and assassins can do a good job on aphids and eggs of other pests. Be sure to learn the difference with ladybird and lacewing larvae as they eat aphids. Often these larvae are mistaken for pests when they can actually destroy large numbers of aphids.
Support host plants for parasitic wasps. They feed on nectar, so try yarrow or dill and other tempting flowers. These are the complete opposite of predatory wasps like Yellowjackets. Parasitic wasps inject their eggs into specific hosts such as Japanese beetle larvae. They don’t sting people or confuse bee populations. When spraying insecticides, these beneficial insects are also often hit. This can escalate the pest situation instead of fixing it.
solutions
Good pest control is about prevention, conservation and healthy ecosystems.
Insecticides are available for some of these insects. However, I am not an advocate of them. Useful insect friends can be damaged depending on their use and application. Soil organisms are affected. The accumulation occurs over time. Birds eat the sprayed beetles. And the cycle continues.
Start planning for next summer. Design your garden for pest control. Spread out plants that often attract the pests in your garden, knowing that each garden or growing area is a mini-ecosystem with its own needs. For example, avoid planting all tomatoes in the same area. Use a multicultural approach.
Add row cover or net, especially for newer or more delicate plants. This can deter some flying insects. Row covers can also help better contain beneficial insects if you have installed ladybugs from the gardening store, for example.
Simply picking and chopping bad pests works great. Teach a few children to hand-pick bugs and grasshoppers. Put bugs in a bucket of soapy water to keep them from escaping. Check the underside of the leaves and mash any eggs found.
Night hunting can be fun. Put on your headlamp and pick snails by following their slimy, shimmering trail.
If the situation gets worse, consider organic controls like soapy water or neem oil. These work well on eggs and larval stages or aphids. Insects with soft outer bodies are suffocated by the application. Always use at night after other pollinators and insects have gone to bed. For more instructions on how to use oils and soaps safely, see 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 excerpt of what is happening in our gardens right now. Here’s a greeting to the snails, earwigs, ants, and predatory wasps, to name a few other pests. See you, but our attention right now is on other creepy crawly animals.
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