Japanese beetle (Popillia japonica)
European chafer (Amphimallon majale)
Southern masked chafer (Cyclocephala lurida)
Black turfgrass ataenius (Ataenius spretulus)
Pest description and crop damage White grubs are the larvae of a number of scarab beetle species. Destructive turfgrass pests found in the Pacific Northwest in the scarab beetle family include the invasive Japanese beetle (Popillia japonica), European chafer (Amphimallon majale), Southern masked chafer (Cyclocephala lurida), and black turfgrass ataenius (BTA, Ataenius spretulus). The adult Japanese beetle is 0.5 inch in length with iridescent, copper-colored wing covers and a green thorax and head. The adult European chafer is 0.5 inch in length with light brown or tan head, thorax, abdomen and wing covers. The insect's eyes are dark brown to black. The Southern masked chafer is very similar in appearance to the European chafer with the exception of a dark brown to black head. Black turfgrass ataenius adults are non-descript shiny black beetles that are 0.25 inch in length. Adult Japanese beetle and chafer are observed as early as May with a peak in population in early July. Adult Japanese beetle and chafer are much larger than adult billbug, which is 0.375 inch in length, black in color, with a distinct snout. The May beetle (Serica spp.) and the 10-lined June beetle (Polyphylla spp.) are also found in the Pacific Northwest but are rarely detrimental to turfgrass.
The Japanese beetle and chafer spend most of their life cycle (July to the following May) underground as root feeding larvae or grubs. These grubs have robust, cream-color bodies, dark-brown heads and six legs and reach a length of 1 inch in the fall. Recently, BTA larvae damage has been observed in the early spring (April to May) in Western Oregon. These grubs have a similar appearance to Japanese beetles and chafers but are ¼ of the size. Mammals (skunks, racoons and birds) will uproot large sections of turf in the fall when feeding on these grubs. Grubs that make it through the fall and winter months will produce damage in the following spring and summer months. Damage at this time appears as patches of turf that are not anchored to the soil and are prone to drought and heat stress despite regular irrigation. Populations of Japanese beetle and chafer are most prevalent in the Seattle/Tacoma area, with small satellite populations observed in the Portland area.
Biology and life cycle Adult Japanese beetle and European chafer are found flying in June and July. The mature or late instar larval populations cause the most damage from October to the subsequent May. Black turfgrass ataenius can have multiple generations per year with larvae feeding in the early spring and early fall.
Scouting and thresholds Scouting should be initiated in the fall months (August and September), before larvae reach maturity or the third instar. At this time damage will increase and insecticide will be less effective. Mammal predation will begin in the fall and continue in the spring. Insects surviving to the spring will produce visible damage in the late spring and summer months. Symptoms will include heat and drought stress, and a compromised root system. Action thresholds are between 5 to 10 larvae for sq ft in well-maintained turfgrass. Scout in the top 2 inches of the soil using a shovel. With the small grub species BTA, 10 to 12 grubs per sq ft in high-value turfgrass and 50 grubs per sq ft for home lawns.
Management-cultural practices
Frequent irrigation will be required to sustain turfgrass growth when infestations of Japanese beetle and chafer are not treated in the fall. The larvae feed on the root systems, comprising the plants' drought stress.
Management-biological control
- Beneficial nematodes
Management-chemical control
Products for home use:
- bifenthrin
- carbaryl
- chlorantraniliprole
- imidacloprid-Some neonicotinoids have been banned from use on public properties
- permethrin
- spinosad
Products for commercial use:
- acephate
- azadiractin-OMRI-listed for organic use.
- bifenthrin-Restricted use
- carbaryl
- chlorantraniliprole
- clothianidin-Some neonicotinoids have been banned from use on public properties.
- dinotefuran-Some neonicotinoids have been banned from use on public properties.
- imidacloprid-Some neonicotinoids have been banned from use on public properties.
- spinosad
- thiamethoxam-Some neonicotinoids have been banned from use on public properties.
- trichlorfon
- tetraniliprole (Tetrino)