Grubworm, White Grubs

Description Adults are 1/2 to 5/8 inch long, reddish brown. The white-headed beetle is a “C” shaped larva, up to 1” long, with a cream-colored body and a brown head. There are three pairs of legs, one on 

each of the first three segments behind the head.

There are more than 100 species of P. coccineus in Texas from several genera (e.g., Cyclocephala, Phyllophaga, etc.), and they are thought to be whiteleaf beetles, may beetles, and geneva beetles. The most common, however, is Phyllophaga crinita. Their biology is similar, but species differ in distribution, habitat preference, life cycle length, and seasonal occurrence. Other common species include the southern masked chafer, Cyclocephala immaculata (Oliver), and the green June beetle, Cotinis nitida (Linnaeus). One notable member of the family Coccinellidae, the Japanese beetle, Popillia japonica, was introduced in the northeastern United States and has migrated west and south, but has not been detected in Texas to date.

Life Cycle: Adults begin to emerge in the spring. While adults are in flight, large numbers of beetles may be attracted to lighting. Peak flight occurs in mid to late June in central Texas. Females are less attracted to lighting and tunnel 2 to 5 inches into the soil to lay eggs; in 3 to 4 weeks the tiny larvae hatch from the eggs and develop through three stages, the first two lasting about 3 weeks. The last larval stage remains in the soil from fall to spring. In spring and early summer, the white grubs pupate 3 to 6 inches deep in the soil. Adults emerge from pupae in about 3 weeks, one generation per year, although in north Texas it can take up to 2 years.

Habitat, feeding habitat: mouthparts for chewing. Phyllophaga crinita is common on Texas turfgrasses, especially bermudagrass, St. Augustine grass, and tall fescue. When large numbers of grubs are eaten, the turf turns yellow and dies. Severely damaged turf may be “rolled up” like a carpet. Grubs also eat weeds, vegetable transplants, and the roots of ornamental plants. In agriculture, they are important pests of forage, corn, sorghum, and sugarcane. The most serious damage to plants is caused by the large (third stage or age) leaf beetle, which feeds on roots from fall through spring. When tilling the soil in the garden or sifting through the soil under damaged turfgrass, white-bellied beetles are often encountered. Adults can be found in abundance around lights in the spring.