Chinch Bugs Pest Note

Information on chinch bugs can also be seen on the Healthy Canadians website.

Chinch bugs: What are they?

The hairy chinch bug is a common type of chinch bug in Eastern Canada.  With their piercing-sucking mouthparts, they feed on the sap of grass plants. They prefer bentgrasses, but will attack many other lawn grasses like bluegrass and varieties of red fescue.

Chinch bugs are black with a white spot on the back between the wing pads. Adult chinch bugs have white wings folded over their backs, and are 4 mm (.16 inches) in length. The immature chinch bug, the nymph, is bright red with distinctive white bands across the back. As it matures, its colouring will change from orange to brown, and finally black. Nymphs do not have wings.

Adult chinch bugs winter hibernate in partially protected areas (under shrubs or around foundations of houses). As the weather warms in the spring, they move into open areas where the females begin laying eggs over the course of a month.

The females will lay 200 to 300 eggs on the lower leaves or roots of the grass. Immature nymphs emerge within a few weeks and undergo five moults (shedding their skin) before reaching adulthood. The nymphs do most of the damage to the grass during this period, generally during the month of June. Nymphs become adults by July with the next generation appearing in August or September, before hibernating for the winter.

What can they do?

Chinch bugs feed by sucking the sap from the crown and stems of turf grasses. This damage shows up as irregular yellow patches, which will spread over the summer. The grass may turn brown and die if feeding continues unchecked, and a severe infestation of chinch bugs can destroy an entire lawn.

The damage caused by chinch bugs appears quickly in hot weather. With most of the damage in open, sunny areas, this may be mistaken for drought damage. There are several ways to confirm an infestation (see Monitoring for more information).

How can I manage them?

Chinch bugs like poorly tended lawns with compacted soils, accumulations of thatch, and a lack of moisture or an excess of nitrogen. Maintaining your lawn properly will discourage infestations and improve tolerance to damage. Some helpful practices include the following:

• If replanting grass, choose an insect-resistant, endophytic variety of tall fescue or rye grass (endophytes are naturally occurring fungi that kill lawn pests, including chinch bugs).
• Aerate the lawn in spring to reduce soil compaction.
• Remove thick layers of thatch (organic debris on the surface of the soil) in the fall, while keeping in mind that some thatch may be needed to prevent winterkill in cold regions.
• Do not over-fertilize since this will encourage greater insect activity.
• Use water-insoluble or slow-release nitrogen fertilizers.
• Use 1 kg of nitrogen per 100 m² (approximately 2 lb per 1000 ft²) should be enough for most lawns.
• Water the lawn thoroughly but infrequently during the summer.
• Keep soil moist to a depth of 6 to 8 cm (2.5 to 3.5 inches).
• Do not cut the grass too short-a length of 6 to 7.5 cm (2.5 to 3 inches) will help avoid stressing the grass.
• Add agricultural limestone to the soil with a pH below 6.5.

Predators

Natural predators and parasites serve to keep chinch bug numbers under control. The big-eyed bug 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 will parasitize chinch bug eggs under favourable conditions, preventing them from hatching.

These predators occur naturally, or can be bought from a commercial insectary.

Monitoring

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 adult chinch bugs. These bugs avoid the light and may hide in soil crevices. The following flotation method can help in cases where the bugs are not readily visible:

1. Cut the bottom out of a coffee can or large juice can and force it 5 cm (two inches) into the turf surface.
2. Fill the can with soapy water, adding more water if the level recedes.
3. Wait 5 to 10 minutes, if you have chinch bugs, they will float to the top of the can.
4. Try this in several areas of the lawn, including lawn edges. If there are 5 to 10 chinch bugs in the can, the infestation is serious enough to damage turf.

Healthy turf should be able to tolerate a level of two or three bugs per can. However, turf that is in poor condition or stressed by hot, dry weather may not tolerate even a low-level infestation.

Pesticides

An infestation of chinch bugs can be treated with pesticides that are available to consumers. Before buying a pesticide, check the label to make sure that it 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.