Young grubs hatch in late summer and feed on roots through the fall. Mature grubs become inactive as cold weather approaches, and spend the winter in the soil. In spring, these mature grubs become active again and will continue feeding on roots until early summer.
Adult beetles begin to emerge in late June and throughout the summer. Adults feed and will mate well into early fall. Mated females lay their eggs in excavated soil cavities.
How to Control Grubs
Lawn areas can be treated with an application of milky disease spores, spores of the bacterium Bacillus popillae. The grubs ingest these bacterial spores, which germinate and reproduce within the grub's body and ultimately kill it. Over several years, the milky spore bacteria will build up in the soil and acts as a natural suppressant to grub infestations. No chemical pesticides should be used on the lawn simultaneously, as this can affect the milky spore's efficacy.
Another naturally-occurring bacteria, Bacillus thuringiensis japonensis (Btj) may also be used to control Japanese beetle grubs. Btj is applied to the soil, and grubs ingest it. Btj destroys the grub's digestive system and ultimately kills the larva.
A beneficial nematode, Heterorhabditis bacteriophora, also works to control Japanese beetle grubs. Nematodes are microscopic parasitic roundworms that transport and feed on bacteria. When they find a grub, the nematodes penetrate the larva and inoculate it with bacteria, which quickly multiply within the grub's body. The nematode then feeds on the bacteria.
Some chemical pesticides are registered for control of Japanese beetle grubs. These pesticides should be applied in July or August, when young grubs are feeding.
How to Control Adults
Where there is one Japanese beetle, there will soon be ten, so hand picking the earliest arrivals can help keep numbers down significantly. In the early morning, beetles are sluggish and can be shaken from branches into a bucket of soapy water.
If Japanese beetle populations are high in your area, beetle control may include making smart decisions about what to plant in your yard. Japanese beetles love roses, grapes, lindens, sassafras, Japanese maple, and purple-leaf plums, so these plants should be avoided if Japanese beetle damage is a concern.
Blue Seal stores also sell pheromone traps for Japanese beetles like the Bonide Beetle Bagger Trap. A dual release floral and pheromone lure. Which will protect 5000 sq.ft, all season long! We also carry replacement lures for use with the Beetle Bagger Trap.
There are various options for chemical pesticides many which are specifically for control of adult Japanese beetles. These pesticides are applied to the foliage of susceptible plants. Your local Blue Seal carries a variety of chemical control options.
Bonide Eight Garden Dust
Permethrin 0.125%. An outstanding vegetable garden insecticide. Which offers contact and residual control for up to 4 weeks. Kills and repells virtually any insect pest common to home gardens. Great for Japanese Beetles on roses & flowers. Colored green to blend with foliage. Short days to harvest intervals.
Bonide Beetle Killer
Lamda-Cyhalothrin .5 concentrate. Provides the punch in this new product to knock out even the toughest beetles, like colorado potato, japanese, mexican bean, asian lady, asian longhorn and others. Low odor, non staining formula quickly kills and repels for up to 8 weeks. Great for vegetable and flower gardens (treats up to 16000 sq. ft.), as well as trees, shrubs, turf & ornamentals. Comes with our "Twist and Shoot" adjustable sprayer to reach trees up to 25' tall.
Bonide Japanese Beetle Killer RTU
Natural pyrethrum for quick and easy kill of Japanese beetles. Kills Japanese Beetles and other insects on vegetables, flowers, ornamentals, trees and shrubs. Can be used indoors, outdoors or in greenhouses.
If you're uncertain on which treatment plan would be the best for you. Consult with your local Blue Seal expert or a local agricultural office for specific information on selecting and using pesticides in your area.