This information is specific to Ohio and may nor may not be applicable to your area. Grubs can be very damaging to lawns if the population is high, but there are now effective, safe-to-use products available that have low toxicities, fairly long residuals, and less adverse effects on beneficial insects. So timing is not as critical as it used to be with the traditional grub products. The effectiveness of both products is more than 90 percent inThe Ohio State studies, topping the list of insecticides used in home lawns for grub control. Imidacloprid is one of the insecticides that came on the homeowner market in 1996. This is available as a granular product as well as a ready-to-spray product. It can be applied from mid-May to mid-August for control of Japanese beetle and masked chafer grubs. If applied mid-May to early June, several other lawn pests are also controlled, including billbugs and the first generations of both chinch bugs and sod webworm. Imidacloprid has to be applied BEFORE the new generation of grubs is discovered in August, and is therefore useful in lawns with a history of grub problems. DO NOT apply earlier than mid-May, or it might not be effective by the time eggs hatch in late July to early August. Another new grub insecticide came on the homeowner market in spring of 1999; halofenozide (molt-accelerating compound halofenozide). Wait to apply this insecticide until early June. This will control both white grubs and billbugs. An advantage of this product is that it can be applied after the new generation of grubs is discovered in August, mid- to late in the month. This is a more integrated pest management approach, targeting the pest population directly once it is discovered and after determining that control is needed. Read and follow all pesticide label instructions.