Japanese beetle – Squish, squash, soak

OK folks the unwanted Japanese beetle has arrived to local gardens. First appearing in eastern Iowa in 1994, this beetle devours over 300 types of garden plants and flowers, favorites being roses, grapes and linden trees. These beetles look similar to a June bug – but have a distinctive row of 5 white spots of tufted hair on each side of the abdomen.

Just to be clear, this beetle invader is not the Emerald Ash Borer, which threatens our ash trees; nor the Asian Ladybeetle, the orange spotted ladybug which evades homes in the fall. We have been very fortunate not to have had serious numbers of the Japanese beetle here yet. Last week however, I received several reports from area Master Gardeners announcing that this pest is now in our area.

Japanese beetles typically appear starting at the end of June, through the month of July, to feed, mate and lay eggs. Adults emerge from the soil, following a larval stage that overwinters as white, C-shaped grubs which feed on the roots of grass in the lawn. If you have visited gardens with Japanese beetles in southern or eastern Iowa, you will have seen the devastating damage to flowers and plants this insect can do.

One strategy of control 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.

For further information on the Japanese beetle, visit: www.ipm.iastate.edu/ipm/iiin/node/125

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.

For further information on garden insect pests or other gardening questions, contact Yvonne McCormick at yvonne@iastate.edu