So many different types of perennial plants are now available to homeowners, it makes planning and growing a perennial garden a really joy. Each gardener can create a space that fulfills their unique vision of beauty. However, while enjoying your garden it’s also a good idea to keep an eye out for several common insects that can put a damper on your plant’s health, including aphids and plant bugs.
Aphids are small, pear-shaped, soft-boded insects that feed by sucking sap from plants through their straw-like mouth. They can reproduce very quickly, with multiple generations of insects each summer. Despite their size, large colonies of aphids can greatly reduce plant vigor. Their feeding often causes leaf cupping and distortion, and their secretion of excess plant sugars, called “honeydew”, frequently results in a black, sooty mold. Almost every plant has some type of aphids that feeds on it. Aphids are a major prey insect species, serving as a food source for lady bugs, lacewing larvae, spiders, and many more. Often these predatory insects will show up after aphid populations have built up to a high level. Syringing, or spraying plants off with a strong jet of water, can often bring aphid populations under control. Applications of insecticidal soap or permethrin, either alone or in conjunction with a soil drench of imidacloprid is recommended for control.
Tarnished, four-lined and phlox plant bugs can also cause problems in the perennial garden. Plant bugs have piercing-sucking mouthparts like aphids and in some cases their saliva is also toxic, causing sunken, dark spots in the leaves where the plant cells have died. Tarnished plant bug is a small, 1/4” long, light-brown insect that feeds on many plants, both ornamentals, vegetables and fruits, in the landscape. Feeding on flower buds causes them to die and fall off, or not open properly. Dahlias and plants in the aster family are frequent victims. Four-lined plant bug adults are greenish-yellow with four black stripes on the wing covers. Their feeding causes round, sunken dead spots on the foliage, which is usually tan in color, but may also be nearly white or almost black. Phlox plant bugs are dull orange to reddish with a black stripe down their back. They feed exclusively on phlox where their activity causes yellow stippling on the leaves. Control plant bugs by removing weeds around garden areas to eliminate overwintering sites. Spray affected plants as soon as damage is noticed with carbaryl or permethrin. Repeat applications may be necessary for good control. Cut down old plant stalks after the first frost, and remove all debris from the garden.
Sarah Browning is a Horticulture Extension Educator with University of Nebraska- Lincoln Extension in Dodge and Saunders Counties. She can be contacted by phone at 727-2775: by mail at 1206 W. 23rd Street, Fremont, NE 68025: or by e-mail at sbrowning2@unl.edu
