The adult of the white grub is the Japanese Beetle, May beetle or June beetle. The larva, which is "C"-shaped with a white body and tan or brown head, damages lawns and gardens by feeding on grass roots. The adult beetles feed on over 275 plant species including roses, ornamentals, deciduous fruit trees, vegetables, grasses, and weeds.
A fully-grown larva is roughly the size of your little finger. White grubs overwinter as larvae and are ready to start feeding on roots as the soil warms up in the spring. Depending on the species, a life cycle may require one, two, or more years. Damage results both from larvae feeding on roots as well as the attraction of moles to the larvae.
Controlling Grubs - Larvae Control
- Treat with a combination of Milky Spore and NemaSeek Beneficial Nematodes in either the spring or the fall. The nematodes help to distribute the Milky Spore and this combination also works synergistically to most effectively control the grubs. Milky Spore only has to be applied once.
- Treat again with NemaSeek Beneficial Nematodes six months after your first application to further distribute the Milky Spore and to eliminate newly developing grubs.
Adult Beetle Control
ARBICO Organics tries to provide pest control solutions for small-scale gardeners as well as larger commercial growing operations. Pyrethrum is the best organic insecticide treatment against Japanese Beetles.
Small Areas and Garden Beetle Control: Direct spray applications of insecticidal soap will kill Japanese Beetles on contact but does not provide any residual protection. Use Safer BioNeem (a combination of insecticidal soap and Neem oil), but keep in mind that Neem can be damaging to plants that are herbaceous or "sensitive," and in those situations, you might want to use a Pyrethrum spray (Take Down Garden Spray).
Large Area Beetle Control: Use PyGanic EC 1.4. This is a pyrethrum concentrate that is effective against hundreds of insects, including the Japanese Beetle. If the water in the area to be treated is alkaline, consider adding Citric Acid to lower the pH to a mid-range of approximately 7.
Related Article: Japanese Beetles - Beetle Mania.