Life Above and Below Ground

Short-horned grasshoppers (family Acrididae) are commonly found in Montana eating plant material and basking in the sun. Grasshoppers thrive during hot summer months, and their populations fluctuate based on weather conditions. Local populations typically increase after several consecutive dry summers. Warmer winters may also contribute to population growth, as larvae are more likely to survive in milder conditions (Marshall 2006).

This grasshopper and wasp pair was spotted in dry, low-elevation grasslands of the Sapphire Mountains on July 29, 2015.

The black, thread-waisted wasp (family Sphecidae) is almost half the size of the grasshopper it carries. She may live amongst other wasps, but as a solitary wasp, she attends to her own nest. Thread-waisted wasps are also sun-lovers and are specialized grasshopper predators (Marshall 2006). Female wasps hunt for insect prey, then sting and paralyze them. She begins the slow journey to her nest, exposing her to predators while she carries the large load. When threatened, she can flee quickly, leaving her paralyzed prey behind and return to continue the journey. She will bring her prey to an underground nest to lay a single egg on it (Marshall 2006). The wasp’s venom helps to preserve her prey until the nymph hatches (Arnett 1985). With a food source secured, the adult female will cover the burrow entrance and begin the search for the next host.

References

Arnett, R. H. (1985). American insects: A handbook of the insects of America north of Mexico. New York: Van Nostrand Reinhold.

Marshall, S. A. (2006) Insects: Their Natural History and Diversity : with a Photographic Guide to Insects of Eastern North America. Buffalo, N.Y.: Firefly Books.