Insects in the Soil/Root Zone
White grubs are the immature stages of a number of beetles such as the Japanese beetle, European chafer, Asiatic Garden beetle, Oriental beetle, and June beetle. All are cream-white colored with a hard brown head capsule and 3 pairs of legs. All curl into a characteristic “C” shape. Depending upon the type, they may be 1/8 inch to one inch long.
Correct identification of the grub species and an understanding of the life cycle are critical for optimum control. The best way to identify the species of grub is via inspection of the tail end.
The source for the following information is an article by Dr. Pat Vittum in the University of Massachusetts Turf Program newsletter Turf Notes (Volume 8, Number 2).
- The Japanese beetle is the most common species of grub found in Massachusetts. It has a transverse split in the tail end and a distinctive set of V shaped spines.
- The European chafer is very active inside the Route 495 area. It is identified by the y shaped split in its tail end and two sets of parallel spines.
- The Oriental beetle is a problem mainly in Coastal areas and has a transverse split in its rear end with spines that are parallel to each other.
- The Asiatic garden beetle has a branched split in its rear end and a distinctive semicircle set of spines.
Larvae Grubs feed on roots causing grass to die. They appear April- May and August-October.
Cut 3 sides of a square, 6 inches per side and flip back the sod. Remove grubs from soil around roots and in the ground and place in a container to be counted. Flip turf back in place, press along edges, and water to re-knit patch of turf. Your lawns can tolerate up to 8-10 grubs/foot. Above this level you need to take control.
Renovate or plant alternate groundcover.
Spores of the bacteria “Bacillus popilliae” can be applied directly to the lawn to control Japanese beetle grubs only. The bacteria cause a milky disease which can may take several months to become active. It may remain active for three to five years.
Chemical controls present problems because the chemicals must move down through the turfgrass and into the soil. If you must use pesticides, timing is critical to ensure control. The University of Massachusetts publication, Professional Guide for IPM in Turf in Massachusetts, recommends treating with insecticides between mid-August and September to moist soil if the grub population exceeds threshold levels. Watering in should be conducted immediately after application. If population is not controlled in late summer, controls should be applied in the Spring as soon as grubs are near the surface (normally in April).
Insects in the Blades and Stems of the Grass
Adults have black and white markings on their wings and are about 1/5 inch long. The nymph (immatures) appear similar but do not have wings and often have red or orange markings. DO NOT confuse this pest with the “big-eyed “bug that is a natural predator of the chinch bug. The two look similar but the big-eyed bug has large, bulging eyes. If at least 50%of the “bugs “are big-eyed then the population may be reduced naturally.
Young Bugs suck juices from grasses causing regular, dead patches especially in dry sunny areas with sunny soil. Appear June-end of July.
Spread grass and look for scurrying insects. The flotation method involves removing both ends of a coffee can and pounding it into the ground to a depth of 2-3 inches. Fill the can with water and watch for insects floating to the top.*Do not confuse the pest with its predator, the big eyed bug.
Water lawn adequately. Plant endophytic grasses
If you find at least 50% big-eyed bugs, then the population will reduce naturally. Otherwise use the Fungi – Beauvaria bassiana
If necessary, apply chemicals in mid June
Sod Web Worms
Adults are tan-colored moths, sometimes having a small dark line on the top of each wing. They have a long “snout ”and are cigar-shaped when at rest. They are often seen flying upward as you walk on the field, especially on a Spring evening. The caterpillars range from 1/8 -1 inch long, are greenish-grey and have dark spots along the body. In larger caterpillars, the head capsule is light brown with some dark markings.
Caterpillars cause small yellow brown patches on leaf blades that enlarge into dead patches, especially in sunny areas in July and August
Look for moths flying above the turf in the evening early in the season or for larval excrement later in the season. Use an irritating drench: on a hot sunny day prepare a solution of 1-2 tablespoons of lemon scented dish detergent in 1-2 gallons of water. Pour this into a 2 feet square space along the edge of the damaged area. Count the number of caterpillars that come to the surface within 5 minutes. Rinse turf with clear water to avoid burning.
Renovate using endophytic grasses or plant alternate ground-covers
Baccilus thuringiensis (BT) Parasitic nematodes
Apply insecticides 2-3 weeks after the peak of moth flight activity. Apply late in the day. Water in lightly
Insects in the Thatch
Blue Grass Billbug
Adults are grayish-black, approximately 1/4 –1 inch in length with a long, narrow snout. Larvae are white-cream colored with a hard, brown head capsule and have no legs. They are approximately 1/16-1/4 inch long.
Larvae cause dead grass especially along the edges of paved areas. Resembles salt damage but appears in late July – August.
Watch for adults scurrying along a paved area near mostly bluegrass lawns on sunny days in late May-mid June. Fine saw dusty “frass”(insect excrement) at the base of grass plants are evidence of larval feeding. Tolerance= 12 adults/5mins or 8-12 larvae/square foot.
Renovate with endophytic grasses or plant alternate ground-covers.
Parasitic nematodes. Fungi – Beauvaria bassiana. Biological pesticides.
Treat small larvae in June with pesticides
Check underside of leaves twice a week for aphids. Check transplants for infestations
Beneficial Insects: Parasitic wasps, Ladybugs. Pyrethrins; Insecticidal soap ; Sticky traps; Control the ant population. Ants protect and encourage aphids. Avoid high levels of nitrogen fertilizer. Prune out damaged plant parts
Broad spectrum insecticides
When you see ants try to follow them. They will lead you back to their nest
Sticky traps at base of plants and trees. Diatomaceous earth or silica gel dust outdoors. Use baited discs or boric acid/ sugar indoors. Find the nest and destroy it. Caulk cracks and block any entrances to home. Remove any debris or woodpiles. Seal all food.
Snails and Slugs
Damaging Stage: Adult
Non-Chemical Controls: Homemade traps. Hand pick them off your plants and hiding areas. Vertical copper screen around planting beds. Copper foil wrapped around plant. Iron phosphate. Eliminate where snails and slugs can hide during the day (boards, stones, debris, weedy area around tree trunks etc). Move susceptible plants or vegetable gardens away from these areas
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