Grasshoppers can quickly turn a lush lawn into a ragged, chewed landscape. Controlling an infestation requires a multi-step approach combining precise timing, targeted application methods, and long-term changes to the lawn environment. Successful management focuses on eliminating the pests during their most vulnerable stage while minimizing the impact on the surrounding ecosystem. This guide provides practical solutions for both immediate control and sustained protection of your turf.
Identifying the Target and Optimal Timing
Effective control begins with confirming you are targeting a grasshopper, not a related insect like a cricket or katydid. Grasshoppers are active during the day and possess short, thick antennae, distinguishing them from crickets and katydids, which have much longer, thread-like antennae. Identifying the developmental stage is more significant than the species.
Most grasshopper species spend the winter as eggs, laid in pods 1.25 to 5 centimeters deep in undisturbed areas like weedy borders or fence rows. These eggs hatch in the spring or early summer when soil temperatures warm. The most vulnerable life stage is the nymph, the small, wingless immature form that emerges from the egg pod.
Control is most effective when the population is composed primarily of young nymphs, typically during the first to third instars. This window generally occurs from mid-May through June, before the pests become winged adults capable of flying and dispersing. Adult grasshoppers have tougher exoskeletons, greater mobility, and are resistant to most control methods, making early-season intervention crucial.
Non-Chemical and Biological Control Methods
Several non-chemical and biological options offer targeted control for property owners seeking to minimize synthetic chemicals. A physical barrier, such as a floating row cover, can protect small garden areas by physically excluding the pests. Hand-picking grasshoppers is also viable for small infestations, particularly in the cool, early morning when the insects are sluggish.
Diatomaceous Earth (DE) provides a mechanical control option, working by physical action rather than chemical toxicity. Food-grade DE is a fine powder composed of fossilized aquatic organisms. Its microscopic edges abrade the waxy layer of the grasshopper’s exoskeleton, causing the pest to rapidly lose moisture and die from desiccation within 12 to 24 hours. For application, the fine dust must be spread lightly and evenly across the lawn and foliage on a dry, windless day. DE loses effectiveness when wet and must be reapplied after rain or heavy dew.
Biological baits utilize the naturally occurring pathogen Nosema locustae, a microsporidian that causes a debilitating disease in grasshoppers. This biological control is formulated as a spore-laced bran bait which must be consumed by the pests. While Nosema locustae is slow-acting and more effective against young nymphs, it is non-toxic to pets, wildlife, and humans, making it a selective, long-term tool for managing smaller populations.
Applying Chemical Treatments Safely
When an infestation is severe, chemical treatments can provide rapid knockdown. The most common synthetic options are pyrethroid-based contact sprays, which contain active ingredients such as permethrin or bifenthrin. These sprays kill grasshoppers quickly upon direct contact or when they consume treated vegetation. Because they are contact killers, these products are best applied when grasshoppers are actively present and temperatures are typically below 90°F to prevent plant injury.
Another effective chemical application method involves using granular baits, most commonly formulated with the insecticide carbaryl and mixed with an attractant like wheat bran. Baits are spread over the ground where grasshoppers forage and offer a selective control method, as they only harm insects that ingest the bait. Unlike sprays, baits must be reapplied after irrigation or rainfall to maintain effectiveness on the soil surface.
The most successful strategy is to use border treatments that target nymph populations concentrated in weedy areas adjacent to the lawn. The product label must be consulted for the specific Re-Entry Interval (REI), which is the minimum time required before people and pets can safely return to the treated area. Adhering to the REI, which can range from a few hours to 48 hours, is a mandatory safety protocol protecting family and pets from exposure.
Cultural Practices for Long-Term Prevention
Shifting focus to long-term habitat modification is the final step in grasshopper management. Since grasshoppers prefer to lay eggs in undisturbed soil, a key preventative measure is removing tall weeds and brush from the lawn perimeter. These weedy areas serve as primary egg-laying sites and provide shelter and initial food for emerging nymphs.
Shallow tilling or raking of these undisturbed border areas in late fall or early spring can physically expose the egg pods to cold weather, predators, and desiccation. Disrupting the soil to a depth of 5 centimeters before the spring hatch significantly reduces the number of nymphs that emerge. This mechanical disturbance breaks the overwintering cycle of the pest.
Proper lawn maintenance can make your turf less appealing to migrating grasshoppers. Infrequent, deep watering (aiming for one to one-and-a-half inches per week) promotes a healthy, dense turf that can withstand more feeding pressure. Maintaining a higher mowing height, never removing more than one-third of the blade at a time, encourages a robust lawn less attractive to grasshoppers seeking dry forage.