Insect Control for the Season

Don’t let these dangerous pests destroy your trees and shrubs

If you battled insects like caterpillars, bagworms, and Japanese beetles eating your shrubs and trees or emerald ash borer, you probably will be fighting them again next year. There is an easy way to protect your plants without spraying.

Bayer 12-Month Tree and Shrub Protect and Feed will control (kill) insects in non-fruit bearing trees and shrubs all year. Best of all, it is applied as a soil drench (watered into the roots) – no spraying! The product should be applied in early spring so that your plants are protected when the insects appear.

Don’t need 12-month control for roses and flowers? No worries, Bayer All-In-One Rose and Flower Care will control insects and disease for 6 to 8 weeks. Either way, this is the easiest way to control insects from damaging your valued plants.

Arborvitae and red cedar are the favored host trees of the evergreen bagworm, but cypress, juniper, pine, spruce, apple, birch, black locust, elm, maple, poplar, oak, sycamore, willow, and over 100 other species are also attacked. Leaves and buds are both fair game for food. The bagworm moth’s larvae (above) spin unsightly baglike shelters in tree canopies and can cause serious damage through defoliation.

The bagworm moth (above) has a number of natural enemies — in particular, parasitoid insects, such as ichneumonid wasps — and research at the University of Illinois at Urbana-Champaign has shown that bagworm control by these insects can be enhanced by planting certain flowering plants near trees and shrubs that are susceptible to bagworm infestations. The flowering plants used in the UIUC research were all members of the Asteraceae, or aster family, which includes many species with daisylike blossoms known to attract parasitoids. Among them were a shasta daisy cultivar (Leucanthemum × superbum ‘Alaska’), a cultivar of the Newfoundland aster (Aster novi-belgii ‘Professor Anton Kippenburg’), and the treasure flower (Gazania rigens), a South African native. The bagworm host plant was an arborvitae cultivar (Thuja occidentalis ‘Woodwardii’). In one trial, surrounding host plants with flowers led to a 70 percent increase in the parasitism of bagworms. In another trial, attacks on bagworms by parasitoid insects increased by a factor of three when host plants were surrounded by a high density of daisy flowers. Many plants in the Asteraceae are native to North America.

The Emerald Ash Borer (Agrilus planipennis or EAB) is a green buprestid or jewel beetle native to north-eastern Asia that feeds on ash species. Females lay eggs in bark crevices on ash trees, and larvae feed underneath the bark of ash trees to emerge as adults in one to two years. The Emerald Ash Borer  is responsible for the destruction of tens of millions of ash trees in 30 states. 

The Japanese Beetle (Popillia japonica) was not much of a problem in the United States until about 1919, when this ravenous native of Japan began a serious invasion, probably after hitchhiking to North American on imported ornamental plants. Today, they are a serious nuisance to gardeners and farmers across North America. The adult Japanese beetles are about 3/8-inches long, with a shiny, metallic green body and copper-brown wing covers. However, not all metallic green or copper beetles are Japanese beetles. To make sure you’re dealing with Japanese beetles, check their undersides for five small, white tufts under the wing covers and an additional tuft at the end of the abdomen, (as shown above). 

Gardeners may create order briefly out of chaos, but nature always gets the last word, and what it says is usually untidy by human standards. But I find all states of nature beautiful, and because I want to delight in my garden, not rule it, I just accept my yen to tame the chaos on one day and let the Japanese beetles run riot on the next.

Diane Ackerman, American Poet

Adult Japanese beetles feeding on a peach tree.