THE PROBLEM WITH PESTS

You’ve properly mulched, watered, and prepared your planting bed. But…

…it’s the height of summer and your plants aren’t looking too hot. You’ve already checked whether it has enough water or light, but your favorite rosebush is wilting in spite of itself. Instead of pulling your hair out, perhaps the landscape-destroying culprit is not weather or climate, but pests.

Chicago is no stranger to massive plant die-offs caused by new insects entering the region for the first time. Because they have no natural predators, these guys wreck havoc—with any tree produced from a cutting, not seed, especially vulnerable since this produces a clone rather than a genetically unique tree. As no on can predict the future, it’s hard to know what to avoid planting. But it’s possible to plant a genetically diverse landscape to maximize your design’s ability to bounce back.

Rodents are also a big problem in the city where there is a lot of protective cover for prey and waste is kept closer to the home. Rabbits and rats uninhibited by their natural predators will tunnel and eat their way through your landscape. This could mean dug up planting beds, or even a sudden and unexpected plant death if their rootball is dramatically disturbed.

Whatever the issue, don’t fret. Here is a helpful guide to spotting some of the more common pests of the Chicagoland area.

#1 Japanese Beetle & Lawn Grubs

Like the perfect evil pest, the Japanese beetle has a 1–2 sucker-punch that can make getting rid of an infestation difficult. As larvae, the lawn grubs feed on the roots of cool-season grasses, causing massive lawn damage and die-off. When soil temperatures rise in the spring, the larvae work their way to the surface where they mature and finally emerge as the Japanese beetle starting mid-July onwards. What’s more, conventional Japanese beetle traps could attract more pests to your yard than the trap kills.

If you see a small, localized patch of dead grass be weary: it could be lawn grubs, especially if the spot is slowly growing in size. If it is, you should be able to easily pull the turf up from the ground. If you see grubs, it might be time for treatment. However when they are fully grown as the Japanese beetle, the best mitigation technique is individually pulling each pest from your plants and throwing them into a soapy solution.

#2 Bagworms

A quick glance might tell your brain these brown-colored capsules are pinecones. But they are in fact the sinister bagworm. They can prey on any plant in the landscape, but are particularly attracted to arborvitae and junipers. As a young caterpillar the bagworm devours only parts of the leaves, but as they mature they grow to the point they must consume entire leaves for survival. If there is a particularly bad infestation, an entire tree can be defoliated. If it is deciduous, the plant might bounce back. However if an evergreen looses all of its needles, it is finished.

What’s more, their signature “bag” visually varies from plant to plant as the caterpillar builds for itself a safe cocoon from the species’ leaves. Luckily they are easily removed after the females have laid eggs, usually autumn through spring. As they only reproduce once a growing season, their complete removal from your landscape means their complete removal. Until your neighbors get them, that is…

#3 Rabbits

This ever-present headache is a problem pest for any homeowner in America (and Europe and Africa and…) They’re adorable, we’re all in agreeance. But when they’re mowing down your spring landscape, they’ve gotta go.

The biggest protection against these guys is spring mitigation when new leaf and stem shoots are soft and tasty. You can distract them with their favorite crop—alfalfa or clover—or fertilize with bone or blood meal as a natural deterrent. Reducing protective cover in the landscape creates more visual exposure where rabbits are less likely to tread. Or maybe you’ve been looking for an excuse to build a raised vegetable bed. Fencing these locations in with super hoops and garden fabric is another effective way to help curb this nuisance.

#4 Slugs

If your hostas aren’t doing so hot, slugs might be at work. They are mollusks, like their hard-shelled cousins, and thrive in moist conditions. Contrary to their perceived slow nature, a slug can make quick work of hosta leaves, leaving a lacy mess in its place. Since they need wetness to survive, slugs are usually found chowing down on not just hostas but also bulbs, annuals, and perennials at night when humidity levels are higher.

Like the Japanese beetle, these unwanted pests are best removed by hand. Using a flashlight at night, try to spot the culprits near stressed plants. Likewise place them in a jar of soapy water. Moistened rolled up newspaper underneath leaves and near mulch or weed piles are also a great, easy way of removing slugs as they will climb in to take shelter from the heat of the day. Check these temporary traps in the morning and remove whatever you’ve caught.

#5 Boxwood Mites

Also known as spider mites, these destructive insects love colonizing this usually problem-free evergreen. Japanese boxwoods hold the best resistance to this pest, with many cultivars on the market that boast improved disease resistance as well. But if you’ve got what you got and would like to keep it (especially if you’ve been training your boxwood for years into a giant giraffe), a shrub scrub down is in your future.

Mite-related die-off becomes apparent when the leaves of your boxwood begin to brown. It’s currently speculated the Boxwood Massacre of 2019 was so bad because of rampant disease and insect problems that were exacerbated by a brutally cold winter. If upon closer inspection you see tiny networks of lacy webs, you’ve got spider mites. They weather under the leaf over the winter and in early spring begin to hatch. Once this has started, it will only be 2–3 weeks before a second generation has hatched. Rubbing horticulture oil on the bottoms of leaves is an option, as well as giving your plant a thorough hose down—though you’ll have to be careful to remove them all, else they might return with a vengeance. The cultivar ‘Green Velvet’ showed particular resistance, with ‘Winter Gem’ almost completely wiped out in the Chicagoland area.

#6 Rats

The most notable—and frightening—pest of the city landscape is the rat. This sucker will burrow its way down and throughout your landscape to create a veritable gopher utopia for the purposes of multiplying and expanding. You can’t blame them for striving to survive, but like an unwelcome guest, you can ask them to get the hell out.

Be proactive. If you notice rat droppings, or if you’re seeing tiny holes pop up in your planting bed, you’ve got rats. As their network expands, plant die-off increases as enough tunneling under an established rootball can compromise the plant. For serious infestations, install your planting beds with chickenwire on the surface. This allows for your plants to grow while creating a burrow-proof barrier. Cover trash and keep it as far from the home as possible. As rodents usually skirt the perimeter of the space they’re in, keep garden borders clean and plug any holes along your deck or home with stone or chickenwire to prevent future heachaches.

THE PROBLEM WITH PESTS