Healthy turf contains a variety of predatory insects, mites and other arthropods. Ground beetles and rove beetles readily attack turf caterpillars as well as the eggs of sod webworms and white grubs. A number of tiny flies and wasps also parasitize turf pests. If pesticides are used indiscriminately or as a "preventive," many of the beneficial predators and parasites will be destroyed. This may allow for a rapid reinvasion by the pests with nothing to keep them in check.
Several insect attacking diseases may be found in the soil and turf canopy. Chinch bugs, sod webworms and billbugs often catch a fungal disease which can obliterate a population. In years where above average rainfall occurs, chinch bugs and sod webworms rarely reach pest status.
A few biological controls are available for use in managing turf insects. Most notably the bacterial milky disease of Japanese beetle grubs, Paenibacillus popilliae (Dutky), has been used. In Ohio, this disease rarely causes more than 25-30% infection and is not considered to be a useful control agent.
The bacterium, Bacillus thuringiensis Berliner (Bt), and its toxins has commonly been used to control various caterpillars. Early marketed Bt products were registered for sod webworm control, though there was little effect on the larger sod webworms and virtually no effect on cutworms. Newer strains have had greatly improved activity on these pests. Recently discovered strains of Bt have been discovered that have activity against white grubs. These may be on the market within a few years.
Several insect parasitic nematodes have been successfully reared in commercial quantities, and are beginning to be available for turf insect control. Strains of Steinernema carpocapsae are fairly good in controlling turf caterpillars, especially cutworms on gold course greens and tees, and billbugs. Other strains and species, especially Heterorhabditis bacteriophora, show promise for control of white grubs. Additional studies are needed to develop consistently effective nematodes and to reduce costs.