There are four species of chinch bugs, or Blissus leucopterus spp., that provide for the bulk of turf damage across the country.
The common chinch bug is generally found from South Dakota across to Virginia, with a southernmost border around central Texas through mid-Georgia. The hairy chinch bug co-mingles in the northern range of its common brethren and also extends through the northern states, making it the predominant species in the northeast. There are also a western and southern species that inhabit where their name suggests in the country.
Most chinch bugs overwinter as adults in thatch or around the base of turfgrass plants. Adults become active when daytime temperatures reach 70 F and head out in search of food. Many grains are considered primary food sources, but certainly grasses are on the menu as well.
The hairy chinch bug prefers Kentucky bluegrass, fescues, ryegrasses, bentgrass, and zoysiagrass, while the common chinch bug will feed on Bermudagrass, fescues, Kentucky bluegrass, perennial ryegrass, zoysiagrass, and crabgrass.
The southern chinch bug is a serious pest of St. Augustinegrass but will also occasionally attack Bermudagrass, centipedegrass, zoysiagrass, and bahiagrass. Improved cultivars of St. Augustinegrass once thought to be resistant later have become susceptible, however most endophytically enhanced grasses have been largely resistant.
A chinch bug’s life cycle is that of incomplete metamorphosis meaning that there are three life stages: egg, nymph, and adult. Each nymph will go through five molting stages called instars before becoming adults. The adult females will feed for a bit following spring emergence and begin mating as males are encountered. They will lay eggs into folds in turf leaves or thatch and continue doing so throughout their lives. Each female can lay up to five eggs per day, which can add up to 200 or 300 eggs during her 60 – 80 day life. This means that there can and will be multiple generations.
Northern areas may see two to three generations, while warmer regions could see several. These generations tend to overlap, so many life stages can inhabit a specific area concurrently. The time to egg hatch is dependent on temperatures also, ranging from 20 – 30 days below 70 degrees, and as little as a week over 80.
Chinch bugs do their damage by piercing grass plants and sucking juices. While doing this, they are injecting an anticoagulant which clogs the vascular system of the plant giving it a purplish tint. With clogged conductive tissue, the plant can no longer move water to the leaves, causing it to wilt and die.
Damage ordinarily is first noticeable along concrete or other warmer areas moving outward. Small spots will continue to grow as feeding persists and will be more visible on drought-stressed turf causing some confusion in diagnosis.
Chinch bugs are very tiny and easily overlooked. As adults they measure between 1/6 and 1/5 of an inch. They have black bodies with white wings crossing over their back. Nymphs have the same body structure but lack wings and will generally have a red or orange marking.
Up close inspection will help determine if they are present so you will have to get on your hands and knees. Another option is the coffee can test. You can use a can or cylindrical item that is strong enough to be tapped on. Simply embed the cylinder about 3-inches deep into the soil near the margin of the damaged area, and fill it ¾ of the way with water for about 10 minutes.
You may need to add more water during this time. While continuing to re-fill, look for floating insects because this will help with a positive identification.
Chemical control is usually accomplished with most contact insecticides including synthetic pyrethroids (those “thrins”), carbamates (Sevin), and organophosphates (Acephate - on golf courses only). Arena is also labeled for control but needs to be applied early when activity is just beginning. Duocide is another good option where it is available containing both bifenthrin and sevin. Granular bifenthrin products on fertilizer particles work well, but sprayed applications can be problematic when not applied with low volumes of water - generally below 1 gallon per 1000 square feet especially on high mowed turf like St. Augustinegrass.
Additional irrigation may be required to move sprays down to where the insects are hanging out. There have been instances of resistance, so rotation is extremely important. As always, read the label before application. Visit the University of Georgia Extension website for more pictures to help with identification.
Feel free to contact the Ewing Technical Services Team with any questions.