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The Next Insect Armageddon

By: Sandra Nelson

The cicada Armageddon has ended here. The endless droning has subsided.  I can now walk across my yard without being attacked by miniature flying torpedoes or crunching a plethora of brown carcasses with each step.

I have definitely been enjoying the quiet and have been looking forward to a time of peace in the garden. And then my son-in-law, the arborist, stopped by and announced, “The Japanese beetles are here, and it looks like a bad year.”  I really wanted him to be wrong, but, as usual, it appears that he was right.  They are here  –  and they are hungry.

japanese beetle

Native to northern Japan, it is believed that Japanese beetles (Popillia japonica) arrived in the United States on the roots of nursery stock or in infested iris bulbs destined for the 1915 - 1916 San Diego Panama-California Exposition. At that time, the insects had no natural enemies and the new environment was nearly ideal, so they were not only able to quickly become entrenched in New Jersey, but also in areas far beyond. For some time, they remained in the eastern part of the United States, but research is showing that their path of destruction is expanding well into the westernmost portions of our country. 


Map of continental US showing the status of the Japanese beetle invasion, by county: well established (red), establishing (orange), occurrences reported (yellow), and no occurrences known (white). Black circles indicate sites of beetle collections


The Japanese beetle is a highly destructive species, responsible for both economic and aesthetic damage. California alone reported a potential loss of  well over 6 billion dollars due to Japanese beetle feastings. Iowa also routinely suffers huge economic losses when the adult beetles strip corn of silks before kernels have been formed. 

Japanese beetle on corn


Japanese beetles are voracious eaters. Recent studies have shown that Japanese beetles have over 300 host plants spawning 79 different plant families including small fruits, tree fruits, truck and garden crops, ornamental shrubs, vines and trees. Their underground larvae eat the roots of many different plants, but are particularly fond of healthy turf grasses. Groups of adults can strip a plant of its foliage overnight while grubs and their predators can destroy a lawn in days.

dead grass


Adult Japanese beetles are deceptively beautiful insects. Each about one-half inch in length, beetles have shiny, metallic green bodies that are covered by copper colored wings. They sport five tufts of white hair on each side of their bodies. and one near the top of the abdomen.  Unlike many other beetles, the bodies of Japanese beetle are hard, making them inedible to birds and other predators.

Japanese beetle


For the next 4 to 6 weeks, Japanese beetles will be active here and across the country. During this time period, females emit a pheromone (chemical substance that triggers a response in members of the same species) that attracts males, causing the insects to congregate and subsequently mate. Every 24 to 48 hours throughout their 30 to 45 day lifespans, female Japanese beetles burrow about 3 inches below the ground’s surface and lay on average five or six eggs. They will repeat the cycle until they have laid 40 to 60 eggs. Soon after, the adult beetles die.



The eggs however, remain in the soil for about 7 to 10 days. As swoon as they hatch, the grubs, as they are commonly called, begin feeding on plant roots. Grubs remain at the surface level feeding until October. As temperatures cool, grubs move deeper underground where they remain until spring.  When soil temperatures reach at least 50 degrees F, the underground grubs begin to pupate. About two weeks later, adult beetles emerge and  immediately begin feeding, mating and laying eggs.



Getting rid of these destructive pests can be difficult. When infestations are light, knocking adult beetles into soapy water is an effective control, especially if it is done in the early mornings before they become active. Avoid the use of pheromone lures and traps since they have a tendency to draw more insects than they catch. Chemical insecticides, which are harmful to beneficial insects as well as pests, should be used sparingly since the damage caused by the toxic chemicals can impact ecosystems for generations.  Since the damage caused to most flowering perennials by adult Japanese beetles is often only aesthetic and not life threatening, it’s often best to refrain from chemical treatments.  .



Controlling grubs in a lawn, especially a lush, pampered lawn, can be a complex, multi-step process, but it can be done. Several precisely timed chemical applications and periodic feedings of essential micro-organisms are often necessary. Reputable companies that are in tune with the environment, like the award-winning staff at Embassy Landscape Group, use these newer, more ecologically sound treatments with great success. (The lawn areas, pictured below, at Briarcfliff are just one of their many success stories.)



It looks like my early mornings are going to be busy for the next few weeks. I’ll be out with my bucket of soapy water chasing the little devils before they munch my hibiscus, my crape myrtle and whatever else suits their fancy.

Maybe then there will be a bit of peace in the garden  –  at least until the aphids show up!