Thursday, January 18, 2007
Expertly Itdentifying White Grub Problems
White grubs (sometimes called grub worms) are among the most widespread and destructive insect pests of turf grasses. "White grubs" is the generic term for the larvae of at least 10 different species of beetles in the United States. As larvae, all are generally similar in appearance, habits and the damage they cause, although they mature into different beetles. They damage turf grass by chewing off the roots near the soil surface. To make matters worse, predators such as birds, skunks, raccoons, armadillos and foxes, may dig up infested turf to feed on the grubs, causing more damage. Grubs tend to do most of their damage from late summer to early fall. Shown at left are photos of a typical white grub and an adult Masked Chafer. The Green June Beetle, pictured below, is another adult whose larvae fall into this category. Early symptoms of white grub infestation include gradual thinning, yellowing, wilting in spite of adequate soil moisture and appearance of scattered, irregular dead patches. As damage continues the dead patches join together and increase in size. Turf that is grub-damaged will not be well anchored to the soil; it can be pulled up or rolled back like a carpet, exposing the white larvae. If the damaged turf does not pull up easily, the brown patches usually are from other causes -- dog urine, chemical spills, fertilizer burn, drought, localized dry spot or disease. The presence of moles, flocks of foraging birds or digging by skunks, raccoons or other predators often indicate that grubs are present. Source: Destructive Turf grass Insects by Daniel A. Potter. Photos courtesy of the Texas Agricultural Extension Service.