White grubs feed on the roots of grasses and usually can be found within the top couple inches of soil. The body is creamy white with a reddish-brown head and they have three pairs of legs on the thorax. Normally they will be seen to curve their bodies into a distinctive C-shape and grubs of the larger Colorado species may reach nearly 1 inch long.
Grub Larvae feed on grass roots through summer and early fall. Peak injury occurs in late summer and early fall but some feeding occurs in spring when larvae return to feed on roots as they complete development. On drought-stressed turf, populations of nine or more grubs per square foot can produce visible injury. Higher grub populations can be tolerated on more vigorously growing turfgrass. Some grub feeding occurs in spring, but favorable growing conditions in spring usually allow grass to outgrow visible damage during that time. When soils cool in autumn and approach 60oF white grubs move more deeply into the soil where they remain in a dormant condition until soils warm in spring.
