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Pest, Disease & Weed Timing CalendarsGrasshopper Calendar
Grasshopper outbreaks are driven by the previous year's egg laying and by spring and summer weather. Scouting early, along field margins, gives you the most time to respond.
Key points
- Grasshoppers overwinter as eggs and hatch as soils warm, with timing set by weather.
- Scout margins and egg-laying sites first, and catch small nymphs early.
- Hot, dry weather raises risk, and drought pushes them into crops.
- Keep a map and notes so next year's scouting starts in the right places.
When do grasshoppers hatch?
Most pest grasshoppers pass winter as eggs in the soil, laid in late summer and fall in pods in undisturbed ground such as roadsides, pastures and field edges. Eggs hatch in spring and early summer as soils warm, and the timing differs by species and by weather. Warm springs tend to bring earlier hatch, and cool springs push it later.
Because of this, no single date fits every region. Your state extension service and the state or federal agencies that track grasshoppers can tell you what the hatch looks like in your area.
For example, if you farm near rangeland and see many adults laying eggs in late summer, mark those spots on a map. The following spring, begin checking those exact places as soon as soils warm.
What is the life cycle?
Grasshoppers have incomplete metamorphosis: egg, nymph and adult. Nymphs look like small wingless adults and molt several times as they grow. Adults develop wings, mate and lay eggs. Most species have one generation a year.
Nymphs are the stage when control is generally most effective, because they are small, concentrated near hatching sites and unable to fly. As they age, they disperse and move into crops.
Different species hatch at different times, so you may see small nymphs of one species while another is still in the egg stage. This spreads out the risk and makes repeated visits worthwhile.
Where should you scout first?
Begin in the places where eggs were laid the year before: weedy ditches, fence lines, pasture edges, conservation strips and untilled ground next to crops. Look for young nymphs there in the weeks after hatch. A high count of small nymphs on field margins can signal that damage to nearby crops is likely.
Then walk into the crop. Seedlings and young crops next to margins are at the greatest risk, and feeding often begins at the edge and moves inward.
- Field margins, ditches and fence lines
- Pastures and rangeland next to crops
- Crop edges before the interior
- Record nymph size and species if known
How do you count grasshoppers?
Many extension programs use a count per square yard, taking several samples across the area and averaging them. Others use a sweep net or an estimate while walking. Choose the method your extension service recommends and use it the same way each visit.
Record the stage and the species mix, since some species are more damaging to crops than others and thresholds differ by crop and stage.
Walk the same transects each visit so that you compare the same ground. Mark the start with a flag or a GPS point so another person can repeat the count.
How does weather change the risk?
Hot, dry summers favor grasshoppers by speeding development and, in some years, improving egg survival. Cool, wet spells can slow them and increase disease in nymphs. Drought also pushes grasshoppers out of drying rangeland and into green crops.
Follow the U.S. Drought Monitor and your state alerts, and compare against survey information from the previous fall, when egg surveys sometimes forecast the following year.
A cool, wet June can reduce numbers in some years, but do not count on it, since egg beds laid the previous fall may be large enough to produce a strong hatch anyway.
What can you do beyond scouting?
Cultural steps include keeping field margins managed, tilling or managing weeds before planting where appropriate, and planting trap strips or delaying planting where local guidance supports it. Grazing and rangeland management also affect the problem, so ask your extension office for advice that fits your operation.
If you consider an insecticide, the label is the law. Pre-harvest and grazing intervals apply, pollinator protection is required and applicator licensing varies by state. Timing on nymphs, before they enter the crop, is usually discussed in extension guidance.
If you graze livestock, talk to your extension office about how grazing management affects egg-laying habitat and about any program that helps with large outbreaks.
What records should you keep?
Write down where you found egg beds in fall, where nymphs hatched in spring, dates of first hatch, counts and any treatments. A map of hot spots makes next year's scouting faster.
For crop insurance and conservation programs, written records of pest pressure and actions taken can be useful, and your local USDA service center or insurance agent can explain what is needed.
Sources and further reading
Last reviewed: November 2026. Educational information, ranges only. Confirm timing with your county extension office.