Identifying and Controlling Chinch Bugs

Understand Their Life Cycle, Practice Smart Control

Lawn being overtaken by dead patches

Justin Smith / Getty Images

"Bug" is a slang term used to refer to any insect, but, in the case of chinch bugs, it is also a scientifically accurate term. That is because the chinch bug (genus, Blissus) belongs to the zoological suborder of Heteroptera, commonly referred to as the "true bugs." They are also true pests, causing damage to lawns and sometimes to crops, as well. There are different types that plague different areas of the United States, but all are small enough (less than 1 inch long) to go unnoticed until they begin killing your grass.

Life Cycle and Identification of Chinch Bugs

Chinch bugs develop through three different stages in life: the egg, nymphal, and adult stages:

  • Egg stage: The tiny (1/32 inch) eggs start out white before becoming orange.
  • Nymphal stage: There are five different developmental periods within the nymphal stage, alone. In the earliest stages the nymphs have a lot of orange in them and are extremely small. But in the final stage, they become more black, about 1/8 long, and develop wing pads.
  • Adult stage: Adults are winged and 9/64 inch long. The head and underside are grayish-black; the legs are dark, with a hint of orange. The main identifying feature is the wings: They are mainly white but both contain a triangular black spot at the outer edge.
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The adults overwinter in a state of dormancy in grass and do not become active the following spring until the temperature reaches 70 degrees Fahrenheit. At this time, they begin to feed. Once their nutritional needs are met, mating is not far behind, starting the life cycle all over again.

The eggs are laid in your lawn and hatch anywhere from one to four weeks (depending on weather conditions). Even in the larval (nymphal) stage, these pests cause damage, as the nymphs eat the roots of your grass that lie just below ground level. Worse still, the nymphs mature in July and produce a second generation of chinch bugs, which proceeds to wreak further havoc upon your lawn. Whereas the nymphs feed on your grass underground, the adults eat the above-ground vegetation.

Signs of a Chinch Big Infestation

You may have a chinch bug problem if you see irregularly shaped, discolored patches in areas of your lawn. You will find that watering your grass does not solve the problem. The patches start out yellowish and later turn brown and die. If you do not address the issue properly, the discoloration spreads and may eventually engulf the whole lawn.

A chinch bug infestation becomes more likely if the grass is under stress due to extreme heat and droughty conditions. It is also more likely in some areas of the lawn than others due to their tendency to dry out:

  • Lawn areas that slope in a southerly direction
  • Parts of your lawn running along a driveway or a patio
  • Areas of the lawn with sandy soil and in full sun

In addition to having sunny, dry conditions, the likelihood of a chinch bug infestation also increases if you have a thick layer of thatch on your lawn. Thatch makes for a perfect base for chinch bugs to hide out in and launch attacks from.

Types of Chinch Bugs

It sometimes takes an expert to tell one kind of chinch bug species apart from another (especially in the nymphal stage). But all are similarly destructive. Types of chinch bugs include:

  • The hairy chinch bug (Blissus leucopterus hirtus)
  • The common chinch bug (Blissus leucopterus leucopterus)
  • The Southern chinch bug (Blissus insularis)

Most regions in the United States host at least one type of chinch bug. In the Northeast, the hairy chinch bug is most prevalent. But it is widely found elsewhere, too, as is the aptly named common chinch bug.

The South has its own chinch bug, and the Southern chinch bug may do the most damage of all. This is understandable, due to two considerations:

  • Drought is a contributing factor to infestations of chinch bugs, and drought is a bigger problem in the South than in the North.
  • Winters are shorter in the South. This allows Southern chinch bugs to spend less time in dormancy and more time making pests of themselves.

Plants Damaged by Chinch Bugs

Chinch bugs eat a number of plants in the grass family. Most importantly to the homeowner, they eat a great many types of lawn grasses. Chinch bugs that live in the North eat cool-season grasses, while those that live in the South eat warm-season grasses. Types of grass eaten by chinch bugs include:

  • Barley (Hordeum vulgare)
  • Corn, or "maize" (Zea mais)
  • Common wheat (Triticum aestivum)
  • Bentgrass (Agrostis spp.)
  • Bermuda grass (Cynodon dactylon)
  • Kentucky bluegrass (Poa pratensis)
  • Perennial ryegrass (Lolium perenne)
  • St. Augustine grass (Stenotaphrum secundatum)
  • Tall fescue grass (Festuca arundinacea)
  • Zoysia grass (Zoysia japonica)

But chinch bugs do not simply eat your grass. If that were all that they do, then the damage that they cause would not be nearly so great. The problem is that, in the process of eating your grass, they also inject a poison into it. The poison inhibits water uptake, and the grass dies. By contrast, when groundhogs or rabbit pests eat your grass, they merely trim it; they do not kill it, and so the grass grows right back afterward.

Chinch Bug Control: Organic, Chemical Measures

As with most landscaping problems, it is better to prevent the problem from arising in the first place than to let it happen and then solve it. Preventive control measures have the benefit that they are organic.

Preventing an infestation of chinch bugs is very straightforward, thankfully. Prevention methods are based simply on eliminating the two things that make chinch bug infestations more likely: dryness and thatch. Therefore:

Another preventive measure to take is to introduce to your lawn a healthy population of beneficial insects that prey upon chinch bugs. One example is the ladybug (Hippodamia convergens).

Still, if you fail in prevention, there is a way to treat an existing chinch bug problem. Unhappily, this way involves using chemical insecticides. If you choose this option, look for an insecticide that contains bifenthrin, carbaryl, or Trichlorfon. Follow label instructions carefully, including time of application.

If you suspect you have chinch bugs, though, the first step is to try to detect them (you want to make sure that the patches of dead grass really are due to an infestation and not simply to drought). On a warm, sunny day, inspect the still-green grass next to the discolored patches. Spread the blades carefully with your fingers and peer down to where the grass meets the soil surface. If you see a lot of tiny bugs running around down there, they may be chinch bugs. Capture a few and bring them to your local cooperative extension to get a positive identification.