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Those little (chinch) buggers!

We are often approached by homeowners who want to show us a photo of damage on their lawn, and they expect us to diagnose the problem from a distance. It’s not always that easy, especially if it might be chinch bugs! These minuscule insects, less than one centimetre in length, can cause significant damage to grass under the right conditions. Understanding their biology, identifying their presence, and knowing how to manage them are crucial steps in maintaining healthy lawns.

Chinch bugs are small, black and white insects that primarily feed on the sap of turfgrass. While several species exist, the most notorious for lawn damage in Canada is the hairy chinch bug (Latin name: Blissus leucopterus hirtus). These pests thrive in hot, dry conditions, making summer their peak season for activity. This summer has been particularly bad in Canada, and it is possible that other species of chinch may expand their range northward in response to climate change and urban expansion. Chinch bugs recently spread into Europe in 2019, and they are trying to keep them under quarantine to prevent the spread (Lima et al, 2021). 

Despite their tiny size, chinch bugs can pack a mighty punch. They are equipped with piercing-sucking mouthparts that allow them to draw out the sap from grass blades. As they feed, they inject toxins into the plant tissue, leading to yellowing and eventually the death of the grass. This damage often appears as irregular patches that can expand rapidly if the infestation is severe. The damage is typically more severe on non-irrigated turfgrass, or under high heat or drought conditions. Urban watering restrictions can exacerbate an infestation. The first sign of chinch bug damage is often small yellow patches that resemble drought stress. These patches typically begin in sunny, dry areas of the lawn. As the infestation continues, the yellow patches will expand, turning brown as the grass dies. The affected areas will spread outward in an irregular pattern.

Chinch bug adults will spend the winter under a bush or tree in a state of dormancy. In May, or when the spring daily temperatures are over 21 degrees Celsius, the adults will emerge and lay eggs. Each female can lay up to 200 eggs which take between seven to 30 days to hatch, depending on temperature. The wingless young (called nymphs) can cause significant damage as they feed on the sap from the crown and stems of turfgrasses. The first generation matures around mid-July and will lay eggs soon after. It is possible to find multiple life stages within a stand of grass. In warmer climates, or in particularly warm years, there is a possibility of a short third generation. In fall the adults will seek out a safe place to spend the winter.

The typical lifecycle of the chinch bugs through the months.

Checking for infestations

To confirm chinch bug infestation, you will need to take a close look at the affected areas to find the bugs themselves. The best time to check for chinch bug infestations is the second week of July (in Ontario) or when the bird’s foot trefoil is in full bloom. They are most active in the daytime, and you may spot them at the base of grass blades or by parting the turf. Get up close and personal with the grass, on the edge of the affected area, and scratch your way into the thatch to look for adult bugs which are black with white stripes or younger chinch bugs which are red or orange with a lighter band around the middle. Regularly inspecting lawns, especially during the summer months, can help detect early signs of chinch bug activity. Using a flotation method – something we refer to in the turf world as “the coffee can method” – can be an effective way to monitor populations. If more than 25 chinch bugs per square foot are found, it’s typically recommended to begin management efforts.

The best way to combat chinch bugs is to prevent them from becoming a problem in the first place. Maintaining a healthy turf stand through proper fertilization, irrigation, and mowing practices is the first line of defence. Avoiding excessive nitrogen fertilizer, which can promote lush but weak growth, is also important. For those managing large areas, such as sports fields or commercial properties, developing an integrated pest management (IPM) plan that includes regular monitoring, cultural practices, and the judicious use of pesticides can help maintain turf health and reduce the likelihood of chinch bug infestations.

Another option for chinch bug management is to seed with endophyte-enhanced grasses. These turfgrass varieties have been inoculated or naturally contain beneficial fungi known as endophytes, which live symbiotically within the plant tissues, particularly in the stems, leaves, and seeds. The endophytes produce alkaloid compounds that are toxic or unpalatable to chinch bugs and other insect pests. When chinch bugs feed on these grasses, the metabolites can either repel them or reduce their survival rates, decreasing pest populations. Endophytes have been found in tall fescue, perennial ryegrass, hard fescue, chewings fescue and creeping red fescue.

When a chinch bug infestation develops, prompt action is necessary to prevent further damage. Since damage is more severe under dry conditions, turning on the irrigation can help reduce their impact. Watering deeply and infrequently encourages deeper root growth and makes the lawn less susceptible to damage.

Biocontrol products containing Beauveria bassiana or Metarhizium anisopliae have shown decent efficacy in the field. These fungi will attack through the skin and grow into the body of the bug, essentially decomposing them before they have died. Unfortunately, biocontrol products are not infallible. They are impacted by environmental conditions such as moisture, temperature, and UV exposure. One study demonstrated that a product containing Beauveria dropped in viability from 80 per cent to 10 per cent within three weeks of application (Thompson et al., 2006). To maximize the efficacy of biocontrol products for chinch, applications should be made when the humidity is high, when the UV light is low (late afternoon or cloudy/rainy days), and at warm temperatures (18-29 degrees Celsius). Irrigation after application can also help move the spores deeper into the thatch layer and soil profile, which can provide protection from damaging surface temperatures and UV exposure. Always read the label and follow the instructions accordingly!

In cases of severe infestation, insecticides may be necessary. There are several products registered for use in Canada to use on chinch bugs, but the availability may depend on provincial or regional regulations. Products containing potassium salts of fatty acid and/or pyrethrins (insecticides extracted from chrysanthemum flowers) may be available in regions with pesticide bans. It’s important to follow the label instructions carefully and apply treatments when chinch bugs are most active, typically in the warmer months.

Are they getting worse?

Chinch bugs thrive in hot, dry conditions. Prolonged droughts or water restrictions can weaken turf, allowing chinch bugs to cause more severe damage. Furthermore, as temperatures rise due to climate change, we may see three generations of chinch bug occurring in regions where two generations are currently the norm. If there are three generations, the period during which they feed is prolonged, causing more sustained and extensive damage to the grass. With multiple generations overlapping, it would be more challenging to effectively time control measures. Younger and older chinch bugs might coexist, requiring different strategies for management. More generations can also lead to faster development of resistance to insecticides, which could make chemical control less effective over time.

Chinch bugs, though small, can have a significant impact on the health and appearance of lawns. For turfgrass managers, landscapers, and homeowners, understanding the signs of an infestation and knowing how to manage and prevent these pests is essential. With the right approach, it’s possible to keep these tiny terrors at bay and enjoy a vibrant, green turfgrass stand all season long.

Resources:

• Lima A., Valada, T., Caetano, M.F., Franco, J.C., Ramos, A. P. 2021. First record of the lawn chinch bug Blissus insularis Barber (Hemiptera: Blissidae) in Europe, Phytoparasitica, 49: 539–545.
• Michigan State University Extension. (no date). Chinch bugs. Available: https://www.canr.msu.edu/ipm/diseases/chinch-bug?language_id=
• Ohio State University Extension. 2012. Chinch bugs in turfgrass. Available: https://ohioline.osu.edu/factsheet/HYG-2503-11
• Ontario Ministry of Agriculture, Food and Agribusiness. 2022. Hairy chinch bugs in lawns. Available: https://www.ontario.ca/page/hairy-chinch-bugs-lawns
• Ontario Ministry of Agriculture, Food and Agribusiness. 2024. Debunking endophytes. Available: https://www.ontario.ca/page/debunking-endowphytes
• Thompson, S.R., Brandenburg, R.L., Arends, J.J. 2006. Impact of moisture and UV degradation on Beauveria bassiana (Balsamo) Vuillemin conidial viability in turfgrass. Biological Control, 39: 401–407. 
• University of New Hampshire Extension. 2016. Hairy chinch bug, Pest fact sheet 46. Available: https://extension.unh.edu/resource/hairy-chinch-bug-fact-sheet

Dr. Sara Stricker is the communications and outreach co-ordinator at the Guelph Turfgrass Institute.
Matt Legg is the technical lead at Syngenta Canada.

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