Native to Japan, these beetles were accidentally introduced to New Jersey  in 1916, via imported iris bulbs.PicMonkey Collage

The irony is that these Japanese beetles are not a problem in Japan, where their natural predators (parasitic wasps) control their population. Cooler temperatures and absence of proper larval habitat is also responsible for curtailing their numbers in Japan.

Japanese beetles are voracious feeders. Grubs (baby beetles) feed on grass roots while the adults devour foliage, fruits and flowers of more than 300 species of plants.  It is the insect version of a flash mob.

They enjoy warm weather and come out of the soil when the sun is out, for eating and mating. They are active from mid-June to mid-September & are  most active during the hottest part of the day.

While devouring a plant, the beetle secretes ‘congregation pheromone’ that attracts other Japanese beetles to come to the same area and enjoy the feast. Japanese beetles usually feed in groups and consume the upper portion of plants and trees before consuming down to the rest. They prefer organized destruction!

Beetle traps are available to catch these pests. However, these traps use pheromones to attract these beetles towards itself. It’s said these traps attract more beetles to one’s property, than there actually is!

Hand picking and dropping into soapy water for small problems or spray with insecticidal soaps.  Chemical sprays can also be used such as Ortho or Bayer Insect Control…use recommended directions. 
Japanese Beetle Grubs are America’s No.1 Turf Pests, as they devour the roots of grass, thereby damaging turf.

After mating, by late afternoon, the female burrows her way into the soil (2-4 inches) for laying her eggs. She lays 1-5 eggs every 2-3 days and has the capacity to lay about 60 eggs during her lifespan of 30-45 days. The eggs hatch in 2 weeks time. On hatching, the beetle grubs spend time chewing on grass roots. When the temperature drops in late September, the grubs burrow deeper in the soil and hibernate for the next 10 months.

They then emerge in late May and feed on the roots of turf grasses and vegetable seedlings. By mid-June, they pupate into adults and undergo a full swing feeding and mating activity for the next 4-6 weeks, after which they die off. The average lifespan of an adult Japanese beetle is only 30-45 days. However, the widespread destruction caused by them within this short life of theirs makes one to wish they didn’t even live this long!

The larvae feeding on grass roots, debilitate the ability of the grass to draw enough water from the soil in order to survive the heat. This results in the death of grasses and conduces to large patches of dead lawns. As far as the adults are concerned, they emerge from the soil and feed on shrubs and trees. Voracious eaters as they are, these beetles can strip a fruit tree of its leaves in flat 15 minutes.  

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