THE FACTS

     Grasshoppers make up the largest amount of aboveground biomass of plant feeders on Konza Prairie, with the exception of bison.  This makes them the second most important grazer on the tallgrass prairie.  The impact of grasshoppers on the tallgrass prairie ecosystem and their great abundance, have made them an important species to monitor.

LIFE CYCLE

     Let’s begin with the egg.  Female grasshoppers lay their eggs in the soil as a batch or cluster, protected by a foamy substance that hardens to form an egg pod. The eggs hatch after a period of incubation, often after passing the winter underground before development is complete. The newly hatched grasshopper digs its way to the soil surface and molts, or sheds its old skin to change into a nymph. This is an active form capable of walking, hopping and eating. Several molts follow until the last molt to the adult. Some grasshoppers hatch in the fall and over winter as nymphs or adults. In Kansas you can find these hoppers out sunning or basking on a warm winter afternoon. They particularly enjoy basking on a rock outcropping or bare soil exposed to the sun. When the last molt is complete, the fully formed and reproductively capable adult appears. Adults mate and produce eggs, which the female places in the soil. There is one generation each year. Each species hatches, develops and reproduces on its own life cycle. 

HABITAT

     Grasshoppers thrive in open, sunny environments, like prairies, pastures and fields. They are affected by the weather, especially temperature, wind speed and cloud cover. Their body temperature depends to a great extent on the surrounding air. Body temperatures can be maintained 10-15 degrees C higher than ambient. The best temperature for digestion is 38° C (the same as in humans and other animals). Grasshoppers seek out sunny sites and bask to keep an optimal temperature.

DIET

     Grasshoppers usually feed on plant material. They graze on many kinds of plants from different families, several species of plants in one family or in a few cases, on only one species of plant. Some kinds of grasshoppers also feed on dead plant and animal material, and some are even carnivorous on other insects.

WHY ARE GRASSHOPPERS SO IMPORTANT?

     Grasshoppers are ecologically significant in the prairie. The highest number of species is present in the Great Plains and grasslands of western North America. There are more than 100 species in Kansas and probably more than 40 species on Konza Prairie. They may be the most abundant insects seen. By their numbers, they are the most important plant feeders in the ecosystem. Their combined biomass often reaches or exceeds that of large mammalian grazers, like bison. Damage to native prairie habitats is rare, unlike the possibility of serious damage in field crops, especially in drought years.  Grasshoppers recycle nutrients by dropping clipped plant material and frass (insect excrement), which quickly is degraded by soil organisms. The released nutrients are rapidly available to plants for new or continued growth. 

LONG-TERM INVENTORIES OF GRASSHOPPERS ON KONZA PRAIRIE

PURPOSE: Konza Prairie researchers maintain a long-term inventory of grasshopper species composition and abundance.  Student collections will benefit the LTER researchers by archiving these insects in a quantitative measure that will aid them in their work.

   Click to view the Konza Prairie Biological Station grasshopper species list

METHODS:  Students use insect sweep nets and killing jars to collect grasshoppers from selected areas including native and restored prairie, and burned and unburned prairie.  A sample of 100 sweeps is taken on a transect line; each team of students taking 10 sweeps before carefully transferring the collected insects to the killing jar and alternating with a partner.  In the laboratory, grasshoppers will be sorted by life stage (nymph or adult) and type (band-winged, slant-faced, spur-throated, or really big) and counted.  The adult grasshoppers will then be properly pinned and labeled and placed in the archival collection of the Konza Environmental Education Program.

Click for Grasshopper collection & pinning skills