Introduction
Do you have brown patches on your lawn? Don't be too quick to blame the neighbour's dog - you could have an infestation of chinch bugs.
Damage Caused By Chinch Bugs
Chinch bugs feed by sucking the sap from the crown and stems of turf grasses. This damage appears as irregular yellow patches, which will spread over the summer. The grass may turn brown and die if feeding continues unchecked. A severe infestation of chinch bugs may destroy an entire lawn.
Description of Chinch Bugs
The hairy chinch bug (Blissus leucopterus hirtus) is a common species of chinch bug in eastern areas. It likes to feed on bentgrass, bluegrass and varieties of red fescue. It is black with a white spot on the back between the wing pads. Winged adults have white wings folded over their backs. Adults are 4 mm (a little less than 1/40) in length. The immature chinch bug, the nymph, is bright red with distinctive white bands across the back. It turns first orange, then brown and finally black as it matures. Nymphs do not have wings.
Lifecycle of Chinch Bugs
The adults spend winters congregated under trees and shrubs and on edges of lawns under hedges and flower beds. In spring or early summer when temperatures warm up to 20°C (70°F), the overwintering adults will breed. The females will lay 200-300 eggs over the next month. The eggs are laid on the lower leaves or roots of the grass. The eggs will mature in 30-40 days. The nymphs do most of the damage to the grass during this period, generally during the month of June. Nymphs become adults by July and the next generation will appear in August or September and seek winter hibernation.
Determining the Level of Chinch Bug Infestation
Damage caused by chinch bugs appears quickly in hot weather and
may be mistaken for drought damage. There are several ways to verify an infestation.
Chinch bugs give off an offensive odour when crushed. If your lawn has a noticeable
odour when walked on, you could have a large infestation.
Spread the grass and check the soil surface for red nymphs or black
adults. Chinch bugs avoid the light and may hide in soil crevices. The flotation
method can help in cases where the bugs are not readily visible.
- Cut the bottom out of a coffee can or large juice can and force it 5 cm (2") into the turf surface. Fill the can with soapy water, adding more water if the level recedes. Wait 5-10 minutes. If you have chinch bugs, they will float to the top of the can. Try this in several areas of the lawn, including lawn edges
- If there are 5-10 chinch bugs in the can, the infestation is serious enough to damage turf in good condition. Healthy turf should be able to tolerate a level of 2 or 3 bugs per can. Turf that is in poor condition or stressed by hot, dry weather may not tolerate a
low-level infestation.
Preventative Measures: Good Lawn Management
Chinch bugs prefer poorly tended lawns with compacted soils, accumulations
of thatch, a lack of moisture or an excess of nitrogen. Proper lawn maintenance
will discourage infestations and improve tolerance to damage. Some helpful
practices include the following:
if replanting grass, choosing an insect-resistant, endophytic variety of tall
fescue or ryegrass (endophytes are naturally occurring fungi that kill lawn
pests, including chinch bugs);
- aerating the lawn in the spring to reduce soil compaction;
- removing thick layers of thatch (organic debris on the surface of the soil)
in the fall, while keeping in mind that some thatch may be desirable to prevent
winterkill in cold regions;
- not overfertilizing, since this will encourage greater insect activity;
- using water-insoluble or slow-release nitrogen fertilizers;
- using 1 kg of nitrogen per 100 m 2 (approximately 2 lb per 1000 ft 2 )
should be adequate for most lawns;
- watering the lawn thoroughly but infrequently during the summer;
- irrigating in a dry period to help the lawn withstand the damage caused
by an infestation;
- keeping soil moist to a depth of 6-8 cm (2.5-3.5 inches);
- not cutting the grass too short - a length of 6-7.5 cm (2.5-3 inches) will
help avoid stressing the grass; and
- adding agricultural limestone to soil with a pH below 6.5.
Beneficial Insects
Natural predators and parasites serve to keep chinch bug numbers under control.
- The big-eyed bug (Geocoris bullatis) likes to dine on its relative, the chinch bug. It looks similar to the chinch bug, but has a wider body, larger head and large, predominant eyes.
- The tiny wasp, Eumicrosoma beneficum, will parasitize chinch bug eggs under favourable conditions, preventing them from hatching.
These predators occur naturally, and may possibly be purchased from a commercial insectary (of beneficial insects).
Monitoring of Chinch Bugs
The soap and flannel trap method of trapping and disposing of chinch bugs can also be used as a monitoring method to determine the level of infestation.
-
Put 30 mL (1 oz) of dishwashing soap in 7 L water and drench a small area of lawn, i.e., 0.2 square metres (2 square feet). A larger area of lawn can be treated by using a hose attachment. The chinch bugs will crawl to the surface of the grass to escape the soap.
- Lay a flannel sheet over the treated area and wait 10-15 minutes. The chinch bugs will crawl onto the sheet, where their feet will become trapped in the flannel nap. They can be vacuumed off the sheet or drowned in a bucket of water.
Using a Pesticide to Control Chinch Bugs
An infestation of chinch bugs can be effectively treated with domestic class products. Before purchasing a pest control product, check the label to make sure that the product is registered for this use.
Treat the entire lawn when damage is first noticed in June. A second application may be necessary in August to kill the second generation. Treating after mid-August is not particularly effective. It is best to wait until the following June.
|
