Scavenging Behavior of Grasshoppers (Orthoptera: Acrididae): Feeding and Thermal Responses to Newly Available Resources

Many grasshopper species feed on dead insects, including other grasshoppers. We observed the responses of grasshoppers to newly available grasshopper cadavers at sites in southwestern Montana. Cadavers were first fed upon by grasshoppers within a mean of 5 min of their placement at one site and within 13.7 min at another. Species differed in the propensity to be the first to arrive at and feed on newly available cadavers. Melanoplus packardii Scudder were relatively more common in samples of the first grasshopppers to arrive at and feed upon cadavers than they were in sweep samples of the local grasshopper communities. Ageneotettix deorum (Scudder), in contrast, were relatively less abundant in samples of feeders than in the community and frequently did not respond to nearby cadavers. The time that elapsed before a cadaver was fed upon by grasshoppers was negatively correlated with soil surface temperature across a range of 16 to 64°C. The rate at which the cadavers were consumed was positively correlated with temperature. At lower temperatures, the rate of cadaver discovery was probably constrained by lower rates of locomotion. At temperatures >50°C, feeding was constrained by thermal stresses that were partially overcome by postural adjustments and microhabitat selection. We discuss the mechanisms by which differences among species could arise and the relationship of the results to our previous study of aggression among grasshoppers at cadavers.