Late Summer Brings New Pest Challenges

By Scout Nelson

Late summer brings warm weather, colorful flowers, and plenty of activity in Minnesota gardens. It also creates good conditions for several common pests. Aphids, thrips, spider mites, Japanese beetles, and lawn grubs can damage flowers, vegetables, shrubs, and lawns. Finding these pests early helps gardeners protect plants before serious damage occurs.

Robin Trott, Extension educator, Douglas County, said gardeners can help their plants remain healthy by watching for early signs of pest activity and using safe control methods. Regular checks can help identify problems before pests spread across the garden.

Aphids are small, soft-bodied insects that may appear green, yellow, black, or red. They often gather on stems and the undersides of leaves. They can cause curled leaves, slow growth, and plant stress. A strong stream of water, insecticidal soap, or neem oil can help control them. Lady beetles and other helpful insects can also reduce aphid numbers.

Thrips are small, slender insects that can leave silvery marks, speckles, and black spots on leaves. They may damage flowers and weaken vegetable plants. Removing damaged plant parts, using insecticidal soap or spinosad, and placing sticky traps can help manage them.

Spider mites become more common during hot, dry weather. These tiny pests cause yellow or speckled leaves and may create fine webbing. Washing leaves, increasing moisture, and using insecticidal soap or horticultural oil can help. Broad insecticides may make the problem worse by killing natural predators.

Japanese beetles can chew leaves and flowers, especially on roses, grapes, linden trees, and zinnias. Hand-picking beetles and placing them in soapy water is one useful control method. Gardeners should avoid baited traps and can use row covers where suitable.

Lawn grubs feed on grass roots and can create brown patches. Skunks and raccoons may dig into lawns while searching for them. Beneficial nematodes and other biological controls can help reduce grub numbers.

Photo Credit: gettyimages-v_zaitsev