Least-Toxic Control of Insects
The Hairy Chinch Bug:
- Is just 4 mm long (Fig.1).
- Is bright red when it first hatches, then darkens from brick red to grey/brown when mature.
- Has a distinctive white band across its abdomen as an immature nymph. (This is eventually covered by the enlarging wings as it grows larger and matures.)
Behaviour & effects
Adult chinch bugs spend the winter under trees and shrubs, on the edges of lawns, under hedges, and in flower beds.
When spring arrives, the adults move into the lawn and start depositing eggs. You'll find nymphs in late May and adults by mid-July.
Chinch bugs have piercing mouth parts that suck the sap from the crown and stems of grass plants. Populations of chinch bugs tend to be clumped together, which initially results in dead patches in a small area. These dead areas (Fig. 2) are brown, irregular sunken patches that can grow together to form larger dead areas.
Chinch bug damage to lawns has increased throughout Ontario. And while all common types of grass in Ontario are susceptible to chinch bug feeding, some types might be more susceptible than others.
Light damage doesn't usually appear until the middle of July. In most of Ontario, you won't notice severe damage until August following several weeks of hot, dry weather.
Detecting Chinch Bugs
Think you might have chinch bugs in your lawn? Follow these steps to know for sure:
- Step 1 - Cut out the bottom and the top of a large can to form a cylinder
- Step 2 - Force the cylinder into your lawn
- Step 3 - Fill the cylinder with water. If you have chinch bugs, they'll soon float to the surface where you can see them (Fig. 3)
If your lawn has little or no damage, take ten of these samples from different parts of your lawn. If you find more than 20 chinch bugs per cylinder, treat your lawn. If you can see obvious damage, take the samples from the healthy grass near the dead patches.
When to check
Check the 2nd or 3rd week of July if you can't see any visible damage. Be aware that this will vary from year to year and from one location to another. At this time in July most eggs have hatched, but there shouldn't be a lot of damage to your lawn.
Treating an infestation at this time also prevents chinch bug feeding during the normally dry period of August.
Controlling Chinch Bugs
You can prevent chinch bugs by:
- Topdressing, vertical cutting, or other thatch-reducing techniques to lessen the chance of infestation.
- Aerating your lawn in late spring and plant grass seeds such as fescues or perennial ryegrass, which can be more resistant to chinch bugs than Kentucky bluegrass.
- Keeping the soil moist to reduce infestations. (Chinch bugs usually do their worst damage during periods of heat and drought.)
Chinch bugs are really hard to control, so if you do find an infestation you'll probably need professional help.