DAMAGE DESCRIPTION:
Gradual turf thinning in enlarging patches that turn brown; roots pruned to 1 inch or less below soil surface; sod easily lifted or rolled back; C-shaped white grub larvae found by lifting sod; adults of most species are active at night, but do not feed on grasses.
HOST GRASSES:
Annual bluegrass, Bentgrasses, Bluegrasses; usually problem in cool season grasses in northern States, but are found in at least 40 States.
LIFE CYCLE:
Adults overwinter in loose soil, pine needles, and leaf litter and begin moving into turfgrass in March or April; Females deposit eggs in soil and thatch; upon hatching, larvae feed on grass roots for 3 to 5 weeks before pupating; most 1st generation adults emerge in mid-July; 2nd generation larvae begin appearing in late July or early August and mature into the overwintering adults by October; these white grub larvae are very similar to other white grubs, but smaller (1/4 inch); accordingly, larger numbers of these grubs (30 to 40 per square foot) must be present before turf injury occurs; beetle overwinters a few inches into the soil or under leaf debris, always near its primary food source; larvae a grayish white grub with brown head, 6 legs, c-shaped; adult a hard shelled beetle.
FACTORS THAT MAY PROMOTE INSECT DAMAGE:
Inadequate irrigation and drought stress may compound damage, if eggs are already hatched; signs of grubs may be skunks, moles raccoons, birds feeding in the turf infested areas; severe drought, though, may dessicate most eggs causing minimal grub populations; moist areas favor grub success.
CULTURAL CONTROL:
Adequate water balance to turfgrass; frequent monitoring below turf for grubs; identifying symptoms of grub damage from Spring to Fall.
CHEMICAL CONTROL:
Pre-irrigation suggested prior to chemical treatments; after application of insecticide, drench into soil root zone with water; timing varies by product; repeat irrigation to keep moving insecticide down; control any thatch, which could impede movement of insecticide; threshold level is 30 to 40 per sq. ft.; adult and larvae insecticides may be different.
| Specific Insecticide Recommendations | ||||
|
Insecticide (chemical name) |
Efficacy |
Application Interval |
Time of Year To Apply |
Example of Products (trade names |
| Bendiocarb (larvae) | Good to Excellent | As needed | Spring to Fall | Turcam |
| Imidacloprid (larvae) | Good to Excellent | As needed | Spring to Fall | Merit |
| Trichlorfon (larvae) | Good to Excellent | As needed | Spring to Fall | Dylox, Pronto, Proxol |
| Ethoprop (adult and larvae) | Good to Excellent | As needed | Spring to Fall | Mocap ( not on bentgrass) |
| Bifenthrin (adult) | Good to Excellent | As needed | Spring to Fall | Talstar |
REFERENCES:
Beard, J. B. 2002. Turfgrass Management for Golf Courses. Second Edition. Ann Harbor Press. Chelsea, Michigan..
Decker, H. F., Decker, J. M. 1988. Lawn Care-A Handbook for Professionals. Prentice Hall. Englewood Cliffs, New Jersey.
Liskey, E., “Turfgrass Insecticides”, Grounds Maintenance, Volume 37, Number 2, February 2002, pp. 8-10.
Turgeon, A. J. 2002. Turfgrass Management. Sixth Edition. Prentice Hall. Upper Saddle River, New Jersey.
Taylor, G. R. - Editor. 2000. Turfgrass Pesticide Recommendations 1999-2000. Extension Publication SCS-1991-01. Texas A&M University. College Station, Texas.