Champion Daylilies
Grubs
Masked chafers are large C-shaped beetle larvae that feed on roots of turfgrass plants. These grubs are white, up to 1 inch (2.5 cm) in length, with dark translucent dorsal stripes, brown head capsules and legs, and a characteristic pattern of bristles on the underside of the posterior end of the abdomen (the raster). Masked chafers have a scattering of bristles, while less commonly encountered May or June beetles have two parallel rows of bristles. Masked chafers are larger than black turf-grass ataenius grubs and have a slight constriction at the forward portion of the abdomen, which helps distinguish them. Adult beetles are golden brown, hairy on the underside of the thorax, and have a darker brown head. Species complete one generation per year over-wintering as mature larvae, which form earthen cells in soil where they pupate. Adult males are attracted to lights at night, mostly from mid-June through July.
Susceptible Species
All turf-grass species are susceptible to masked chafer damage. Damage is usually more serious on ryegrass and bluegrass turf-grasses, whereas fescues are somewhat less affected. Warm-season grasses tend to be the most tolerant of grub feeding.
Damage
Masked chafer grubs feed on roots, resulting in irregular dead patches. Symptoms resemble drought stress and persist even where there is sufficient irrigation. Grub activity can cause the ground to feel spongy; extensive root feeding sometimes allows the turf to be rolled back like a carpet. Most damage usually takes place in late summer or early fall. Digging by vertebrate predators, such as crows, raccoons, skunks, and coyotes, is a common indication of high grub populations.
Management
For turf-grass infested with masked chafers, biological and cultural controls may help reduce their number. If monitoring indicates a need, treatment may be warranted. Commercially available parasitic nematodes are among the treatment options.
White grubs