Beetles in the garden

Horticulture Hints

Many insects are now making their appearance in local area gardens. Among these include the masked chafer beetle and the Japanese beetle. These beetles start their life as grubs in the lawn, and adults then emerge to feed on flowers and garden plants.

The masked chafer beetle has recently emerged and is commonly found in all three area counties. This small member of the Junebug family is about one-half inch long and nearly as tall as it is wide. The color is straw-tan to light brown and there is a dark brown “mask” across the face. Rose gardeners have reported finding these feeding on their roses, with the light colored blooms being favored for the first attack.

Japanese beetles first appeared in eastern Iowa in 1994, and although Webster County has a heavy infestation, they have only been reported as rare occurrences in Hamilton and Humboldt counties. This beetle devours over 300 types of garden plants and flowers, favorites being roses, grapes and linden trees. These beetles have a metallic green thorax and coppery brown wing covers with a distinctive row of 5 white spots of tufted hair on each side of the abdomen.

One strategy of control for these beetles is by hand picking the adults. As a Japanese beetle female can lay 60 eggs per season, each beetle annihilated is that many fewer potential grubs to hatch. Adults live about 2 months. With only a limited number now in our area, advising family, friends and neighbors to hand pick and dispose of any beetles found, may help to slow their spread. Smash beetles by hand, gloves optional, or knock them into a jar of soapy water and destroy.

Did you know? The use of Japanese beetle traps is not recommended. Research advises these traps are not an effective means of control, as the pheromone attractants will invite more Japanese beetles into your yard, to join those already present.

Horticulture Questions? Contact McCormick at for information or advice.