How Grasshoppers Beat the Heat

On the hottest summer days, we humans rely on air conditioning, pools and fans to cool us down. However, in the middle of the prairie, grasshoppers don't have the same luxuries. Instead, they have come up with their own clever trick for beating the heat: climbing. 

In the summer of 2023, our team—a group of Great Plains Science Program researchers working in the prairies of eastern Montana—observed masses of grasshoppers perched high on fence posts, plants and other tall objects on hot days. The following summer, we set out to find out how grasshoppers were using these high perches to key in on optimal temperatures. We set out 20 meter sticks and recorded how high the grasshoppers perched, as well as the temperatures along the sticks at various times during the day. 

As anyone who has cooled down in the shade on a hot day knows, temperatures can vary significantly from place to place. For a grasshopper on the prairie, even a few inches can make a considerable difference in what temperatures they experience. This is what scientists call “microclimate”. In the prairie, the ground receives solar radiation, making it hot. The temperature of sticks in the sun was hottest at the bottom and coolest towards the top of the stick. We found that grasshoppers climbed higher on the sticks during days and times of day when it was hot out. In other words, grasshoppers weren’t just climbing for fun, but to beat the heat!

Our research shows grasshoppers use the different microclimates in their environment to maintain temperatures within a preferred range, from about 89 to 114°F. However, on very hot days we found grasshoppers sitting on surface temperatures up to 140°F, which is remarkable considering the most common grasshopper at our field site (Melanoplus sanguinipes) has an upper thermal limit of 127°F. The grasshoppers living in these high temperature areas were already accessing the coolest temperatures available to them, since they were at the top of the measuring sticks. These results are concerning: late summer temperatures may already be pushing some grasshopper species past their physiological limits. For grasshopper species less able to regulate their temperatures in other ways, these extreme temperatures may harm vulnerable species.

Why does this matter? Grasshoppers aren’t just familiar leaping friends; they play fundamental roles in grassland ecosystems, helping to recycle nutrients and shape plant communities. Like many insects, grasshoppers face challenges as climate change alters the temperatures of their habitats. Insects are particularly susceptible to these temperature changes, as their digestion, growth and survival all depend on staying in their thermal “comfort zone.” While we may turn on our air conditioning or jump in the pool on a blazing day, grasshoppers and thousands of other organisms must rely on the landscapes they inhabit.  

As climate change increases the frequency of intense weather events and steadily raises the average global temperature, planting and reseeding diverse vegetation with varied structures can create critical microclimate refuges that could give grasshoppers and other small animals a fighting chance. We must preserve and restore these landscapes- even the smallest microclimates can make all the difference.