Insecticide Recommendations for Grub Control

Thanks to the University of Minnesota Extension Service for allowing UDAF to post this information!

Insecticides are needed to control grubs, but repeated applications may be necessary because of the relatively short residual effect of the pesticides. Also, cautions about their use must be observed. (See Tables 1a and 1b, and the summary of pesticides.)

Table 1a. Insecticides to control Japanese beetle grubs and adults. Use for grubs when damage is observed. Use for adults when feeding and damage is observed on ornamentals. If a product does not work, switch to a different insecticide.

common name	trade name	use for	class	comment/cautions
bifenthrin	Talstar	adults	pyrethroid	High toxicity to honeybees, birds, fish. Do not use nearer than 100 yards from water.
carbaryl	Sevin	grubs, adults	carbamate	High toxicity to bees, earthworms; moderately toxic to birds, fish. Do not use adjacent to water. Available for homeowner use.
chlorpyrifos	Dursban	grubs, adults	organophosphate	High toxicity to birds, fish. Available only to licensed applicator.
cyfluthrin	Tempo	adults	pyrethroid	High toxicity to birds, fish. Do not use adjacent to water.
deltamethrin	DeltaGard	adults	pyrethroid	High toxicity to birds, fish. Do not use adjacent to water.
diazinon	Diazinon	grubs	organophosphate	High toxicity to birds, fish. Not available for golf course or sod farm. Available for homeowner use.
ethoprop	Mocap	grubs	organophosphate	Toxic to aquatic organisms and wildlife.
halofenozide	Mach2, GrubEX	grubs	diacylhydrazine	Low toxicity to birds, fish. Insect growth regulator. Available for homeowner use.
imidacloprid	Merit	grubs	chloronicotinyl	Low toxicity to birds, fish. Do not use after August 15, instead use diazinon, ethoprop, trichlorfon. Available for homeowner use.
lambda-cyhalothrin	Scimitar, Battle	grubs	pyrethroid	High toxicity to fish.
malathion	Malathion	adults	organophosphate	High toxicity to honeybees. Odor may be a problem in public places.
permethrin	Astro	grubs, adults	pyrethroid	High toxicity to fish, bees. For home lawns only.
trichlorfon	Dylox	grubs	organophosphate	High toxicity to birds, fish. Do not use nearer than 100 yards from water. Available for homeowner use.

Table 1b. Insecticides to control Japanese beetle grubs for use in potting media and containerized stock only.

common name	trade name	class	comment
bifenthrin	Talstar	pyrethroid	Use in potting media.
imidacloprid	Marathon	chloronicotinyl	For use in containers.
telfluthrin	Fireban	pyrethroid	Use in potting media for harmonization plan.

Irrigating after applying an insecticide improves its insect control, though a significant rainfall shortly after the application may reduce the insecticide';s concentration below effective levels. A one-inch or thicker layer of thatch may absorb the insecticide before it can reach the layer of soil where the grub is feeding, also making it ineffective.

Infestations should be checked one week after an insecticide is applied, especially if the original grub population was high.

Available Insecticides

Imidacloprid -- is not fast acting, so use as a preventative control, not as a rescue treatment. Apply imidacloprid between May 15 and August 15. It has minimal risk to birds and fish.

Ethoprop -- can be used as a rescue treatment when damage is observed.

Halofenzide -- is not fast acting, so use as a preventative control, not as a rescue treatment. It mimics an insect hormone and is best applied when adults are active and laying eggs from June to the beginning of August. Minimize thatch since heavy thatch will prevent the insecticide from penetrating to the area where insects are feeding.

Trichlorfon -- is fast-acting, but susceptible to alkaline hydrolysis. It degrades very rapidly in very hard or alkaline water or in a high pH soil. Half of the active ingredients will be degraded in 30 minutes at a pH of 9. Do not lime your lawn just before or after treatment for the same reason. Trichlorfon can be used as a rescue treatment when damage is observed.

Chlorpyrifos -- can be effective against grubs, but is generally not considered a top choice due to the high binding ability of the active ingredient to the thatch. It is a good choice for adult Japanese beetle control.

Diazinon -- can be used for homeowner lawns, but not golf courses or sod farms. It binds strongly to soil. It can be used as a rescue treatment when damage is observed.

Milky spore disease -- is caused by the bacteria Bacillus popilliae and is sold under the names of Japidemic Doom and Milky Spore. Recent trials with these formulations have not reduced Japanese beetle grub numbers in turf.

Insecticide recommendations for adult control

Insecticides may be used to control adult Japanese beetles, but repeated applications may be necessary because some pesticides have relatively short residual effects. A significant rainfall shortly after an application may reduce the insecticide concentration below effective levels (Table 1a).

Cultural control

Use an ecosystem approach to managing Japanese beetles. Carefully select plant species that Japanese beetle adults do not like to feed on, when adding to your landscape or golf course. Certain common landscape plants are inevitably attacked and may be poor landscape choices (Table 2). The nursery industry can reduce Japanese beetle numbers in cultivated areas or containers by eliminating grasses that the grubs feed upon.

Table 2. Avoid ornamentals that are severely attacked by adult Japanese beetles.

avoid		better choice
American chestnut American elm American linden American mountain ash Apple Black cherry Black walnut Cherry	Flowering crabapple Grapes Gray birch Hollyhock Horse chestnut Norway Maple Plum Roses	American elder Arborviate Black oak Boxelder Common lilac Euonymus (all species) Fir Green ash	Hemlock Holly (all species) Juniper Pine Red maple Red oak Rhododendron Scarlet oak	Silver maple Spruce White ash White oak White poplar Yew