insect | Approximate threshold per sq. ft. |
---|---|
Japanese beetle | 8 - 15 larvae |
Oriental beetle | 8 - 15 larvae |
Masked chafer | 6 - 15 larvae |
European chafer | 3 - 8 larvae |
Asiatic garden beetle | 12 - 20 larvae |
May beetle (phyllophaga) | 2 - 4 larvae |
Black turfgrass ataenius | 15 - 80 larvae |
Annual bluegrass weevil | 10 - 80 larvae |
Bluegrass billbug | No good estimate available |
Chinch bug | 30 - 50 nymphs |
Sod webworm, cutworm | No good estimate available |
INSECT |
TURF AREAS TO MONITOR |
WHEN TO MONITOR |
SAMPLING TECHNIQUES* |
---|---|---|---|
White grubs |
All turf |
Adults - mid-June to September Larvae - March to May, July to December |
Adults - pheromone traps (oriental beetle, Japanese beetle) ** Larvae - soil sample |
Ants |
All turf |
Adults - late April to late September |
Adults - count active mounds per unit area |
Billbugs |
All turf, especially Kentucky bluegrass |
Adults - May to early June Larvae - June to August |
Adults - soapy flush Larvae - core float |
Chinch Bugs |
All turf; especially sunny, drought stressed areas and areas with thick thatch and sandy root zones. |
Adults - June to late July |
Adults - can float, visual inspection of soil/thatch interface |
Cutworms |
All turf, especially closely mown areas |
Adults - May to September Larvae - late May to September |
Adults - blacklight trap Larvae - soapy flush |
Sod Webworms | All turf, especially sunny areas, steep slopes & dry banks |
Adults - late June - late August Larvae - Late April - early June |
Adults - visual observation at twilight, blacklight trap Larvae – soapy flush |
* Refer to the table, ‘Insect sampling techniques’ below.
** Use pheromone traps with care. They are useful for determining when beetle adults begin to fly, but can also potentially attract more damaging insects into an area.
Technique |
Description |
---|---|
Soil sample |
Dig three sides of a square, 6 inches on a side (=0.25 sq. ft.) and 4-6 inches deep. Flip upside down on flat surface, e.g., a plywood board. Use a trowel to beat soil and roots on bottom of sod in order to dislodge larvae. Remove larvae and put in a container to count totals. Replace sod, water well, and sod should re-root. Alternatively, use a cup cutter to pull samples (=0.1 sq. ft.). |
Soapy flush |
Add 1 to 2 tablespoons of lemon scented liquid dish detergent to 1 gallon of water; pour over area 2 ft. by 2 ft. Caterpillars, earthworms and adults of some species will be irritated and crawl to the surface within 5 minutes (usually more quickly). Collect caterpillars and/or insect adults and put in a container to count totals. If sampling in mid-summer, rinse the area after counting insects to avoid scalding turf. |
Core float method |
Take a sample with a cup cutter, gently break apart turf and thatch, and look for insects. Place all material in dishpan with lukewarm water. Insects will float to surface. |
Can float method |
Remove the ends from 3 or 4 coffee cans. Pound empty cylinders (wet soil to soften) 2 to 3 inches into ground, fill with water, and wait 5 minutes to count insects floating to the surface. |