Beetle season is here and you may be seeing a specific kind of insect – the Japanese Beetle – flying around. This beetle is a non-native insect that has been migrating and making its way to the West for many years now.
The Japanese Beetle has been a nuisance for decades in the United States, and right now it is mating season for the insect.
They lay their eggs during these warm, moist-weather months, in the grass. The eggs pupate over the winter and early spring.
Lately, they have been having an impact on local gardens in the area, causing frustration to Quad-City gardeners.
Emily Swihart, University of Illinois horticulture educator, says the insects feed on leaves, flowers and fruits of plants.
The Japanese beetle is an annual species that emerges only during this time of year, and dies off after four to six weeks.
“So they emerge right about this time of year…beginning of July where we start seeing them emerge out of the soil where eggs were laid last year,” Swihart said. “They develop into grubs. Those that have developed over the winter, pupated into these beetles which are emerging. They feed, mate, and start the process all over again.”
Luckily, the damage the Japanese beetle can cause is not lethal to plants or humans.
Although the beetles are not deadly, people still care about the aesthetic look of their plants, which can be damaged by the insects.
According to the the Rock Island Botanical Center Head Gardener Dave Searl, one easy way to rid gardens of the adult beetle is to get a bucket of soapy water.
“Mix up some soapy water in a bucket. And one of the defensive mechanisms on these Japanese Beetles is when they’re disturbed they either drop to the ground or fly off real quickly,” he said. “But most of the time they drop to the ground then fly off. So what I do is hold the bucket underneath the plant when they’re feeding. Tap the flower or leaf and they drop into the soapy water.”
The best time of year to manage grubs, to avoid having adult beetles in your gardens the following year, is in August and September. This is usually after the females have laid all their eggs.