Walk a south-facing slope on a warm June afternoon and you’ll see them — little nymphs flicking out of the bunchgrass ahead of your boots. Most years a rancher shrugs and moves on. But after a dry fall and an early, warm spring, those flicks add up to a problem that can strip a pasture before you’ve finished first cutting.
Grasshoppers are easy to ignore until they aren’t. By the time the adults are flying thick in late July, the damage is done and spraying is mostly throwing money at bugs that already ate. The whole game is timing, and right now is when the deck is still in your favor.
Why dry years tip the scale
Grasshoppers lay their eggs in late summer and fall, dropping them into undisturbed soil along field edges, roadsides, fencelines, and overgrazed ridges. Those eggs sit through winter and hatch when soil warms in spring. Cool, wet springs work against them — fungal diseases knock the young nymphs back, and slow green-up means the hatch spreads out. A warm, dry spring does the opposite. The hatch comes off in a tight window, the nymphs survive, and they all hit the grass at once.
That’s the setup across a lot of central and eastern Montana right now. Where moisture has been short, the grass is already behind, and a heavy grasshopper load competing for the same forage your cattle need turns a thin year into a wreck. A bad infestation can take as much grass off a pasture as the herd you turned out on it.
Scout while they’re small
You can’t make a smart decision from the pickup. Get out and count. Walk the rangeland and the field margins where eggs overwinter, and estimate how many hoppers you flush per square yard. A reliable trick is to picture a one-foot-square frame on the ground, count what jumps as you approach a series of those squares, and average it. Light numbers scattered across a big pasture aren’t worth chasing. It’s when you’re consistently seeing a dozen or more per square yard, and they’re young, that you start running the math on whether treatment pays.
Pay attention to size. Grasshoppers go through several nymph stages before they grow wings. The young ones — soft-bodied, wingless, clustered near where they hatched — are cheap and easy to kill and haven’t done much eating yet. Once they hit the third or fourth instar and start spreading out, your control gets harder and the bill goes up. Adults with wings will fly in from a neighbor’s ground the day after you spray, so chasing them is usually a loss.
Also figure out what species you’ve got and where they’re feeding. Some grasshoppers prefer broadleaf plants, some hammer grass, and some don’t do enough damage to rangeland to bother with. A county Extension agent can help you sort the pests from the bystanders before you commit to a treatment.
RAATs and the practical options
The most cost-effective approach on rangeland is the reduced-area treatment, often called RAATs. Instead of blanketing every acre, you spray in alternating strips and leave untreated gaps between them. The hoppers move into the treated swaths and pick up enough product to do the job, while you cover more ground with less chemical. It cuts cost, and it leaves refuge for the beneficial insects and birds that help hold grasshoppers down on their own.
Insect growth regulators that keep nymphs from molting fit this strategy well, but they only work on young, immature hoppers — another reason to scout early. Faster-acting insecticides have their place when numbers are high and the bugs are already bigger. Whatever you reach for, read the label for grazing and haying restrictions, especially on ground you’ll cut soon.
On larger outbreaks, the federal rangeland grasshopper program run through USDA can come into play, particularly where infestations cross property lines and a coordinated, landscape-scale treatment makes more sense than every operation spraying its own patch. That kind of effort takes lead time and neighbors talking to each other, so it’s worth a call now rather than in August.
One more thing worth saying plainly: not every year warrants spraying, and a few grasshoppers in a good grass year aren’t worth the diesel. The decision comes down to numbers, the size of the hoppers, the value of the forage they’re eating, and how dry the rest of the summer looks. But you can only make that call if you’ve looked. Spend an evening this week walking your worst pastures. The bugs will tell you whether you’ve got a problem while there’s still time to do something about it.
