Texas Cooperative Extension Harris County

White Grubs in Texas Turfgrass

M.E. Merchant, Extension Urban Entomologist & R.L. Crocker, Research Entomologist
The Texas A&M University System

White grubs are the larval stage of insects commonly known as May or June beetles (or Junebugs). almost 100 species live in Texas, most of which do not cause significant economic damage to crops or horticultural plantings. A few species, however, commonly damage turfgrass and other cultivated plants.

White grubs, sometimes referred to as grubworms, injure turf by feeding on roots and other underground plant parts. Damaged areas within lawns lose vigor and turn brown (Figure 1). Severely damaged turf can be lifted by hand or rolled up from the ground like a carpet.

golf grub Figure 1. Golf course fairway damaged by white grubs.

The most important turfgrass-infesting white grubs in Texas are the June beetle, Phyllophaga crinita (Figure 2) and the southern masked chafer, Cyclocephala lurida. Warm season grasses like bermudagrass, zoysiagrass, St. Augustinegrass, and buffalograss are attacked readily by both type of white grubs, with most lawn damage occurring during summer and fall months.
whitegrub

Figure 2. Adult white grubs, often called May or June beetles, are commonly attracted to lights at night. The optimal time to treat grub-infested lawns is 5-6 weeks after the peak adult flights.

Cool season grasses such as the fescues, bluegrass, and ryegrass are also susceptible to the June beetle and southern masked chafer, though they tend to be attacked more frequently by a May beetle, Phyllophaga congrua. Damage from May beetles often appears in the spring and early summer, before injury from other white grubs becomes evident. Other white grub species occasionally recorded as pests in Texas turfgrass include Cyclocephala pasadenae and Phyllophaga submucida.

Another interesting kind of white grub is the green June beetle, Cotinus nitida. These rather large grubs feed primarily on decaying organic matter and normally do not injure turf; however, turf can be damaged by their burrowing activity. Larvae are especially common underneath fruit trees, in compost piles, and in soils with high organic content, such as may be found in heavily mulched gardens and flower beds. Daytime resting sites of green June beetle larvae can often be found near such sites and are marked by small mounds of soil on the lawn surface. The larvae have a curious habit of crawling on their backs across the soil surface to move from one site to another. Adults of the green June beetle are velvet-green on the top, metallic green below, and are approximately 1 inch in length. Adults fly during the day and feed on over-ripe fruit.

Resources

For more information contact:

Paul Nester
Extension Agent - IPM
Fire Ant Project
Harris County
Phone: (281) 855-5600

the Texas AgriLife Extension Service - Harris County

the Texas AgriLife Extension Service-Harris County