II.13–1

II.13 What, When, and Where Do Grasshoppers Eat?

Larry Jech

Some species of grasshoppers do not readily take baits.

As a result, the effectiveness of grasshopper control

through bait applications can be limited. Various

researchers have attempted to increase bait effectiveness.

These studies have focused primarily on comparing toxi-

cants, varying applications timing, and varying the

ducted observation studies to improve baits through

better understanding of grasshopper feeding behavior.

Findings of Direct Observations

During the summers of 1990 and 1991, GHIPM Project

experiments involved direct observation of grasshoppers

feeding on host plants in rangelands. The study focused

on species that readily take bait and species that do not.

The study sites were typical prairies in western South

Dakota and North Dakota. The grasshopper densities

were representative of those targeted for bait control pro-

Most of the behavior observed had very little to do with

feeding. Grasshoppers basked in the sun, moved about

their habitat, and exhibited avoidance behavior. Most

observations were of third-instar (young grasshoppers)

to adults.

The study included four common species that are not eas-

ily controlled by bait applications at the standard rate of

1.5 lb/acre containing 2 percent carbaryl. These species

were Amphitornus coloradus (Thomas), Cordillacris oc-

cipitalis (Thomas), Trachyrhachys kiowa Thomas, and

After the air temperature reached 81 °F, the grasshoppers

began to feed. Grasshoppers allowed time for their crops

to empty between feeding sessions and repeated feeding

and resting cycles regularly. The insects generally

groomed their antennae and eyes before feeding, but

grooming apparently was not a prerequisite to feeding.

Feeding continued throughout the day if temperatures

remained below 90 °F. When temperatures rose above

95 °F, the grasshoppers perched on stems or took shelter

under vegetation to avoid excessive heat. While the tem-

significant factor for most of the grasshopper population.

Very little feeding took place when winds exceeded 15

miles per hour (mi/hour) or during cool, cloudy days.

The insects would remain quiet until weather conditions

improved. Grasshoppers also stopped feeding when rain

was imminent. After showers or rains passed and the

ground warmed, grasshoppers returned to feeding.

Although grasshoppers spent one-seventh of their time

moving, the movement appeared to be random. Most of

the time, grasshoppers were on the soil surface and

seemed to be balanced carefully between the need to feed

and to remain hidden.

Grasshoppers were very discriminating in their food

choices. They would sample a blade of grass before

feeding on it and occasionally move back to a portion of

the blade or another blade passed over previously.

T. kiowa, one that does accept bran bait, often would feed

on a plant, move a short distance, and then return to the

same plant and resume feeding. The activity showed the

II.13–2

was to bite a portion out of a leaf margin, leaving it

notched.

Aulocara elliotti and Ageneotettix deorum, the two spe-

cies that readily eat bran bait, often picked up bits of

plant litter from the soil surface and tasted and consumed

those food items in addition to feeding actively on live

tissue. These two species also clipped the leaf tips but

dropped the clippings to the ground and later fed on the

sun-dried clippings. The four species that do not accept

bran bait seldom fed on materials found on the soil sur-

midleaf, and at the leaf base. Grasshoppers were

allowed to browse for 8 hours. Grasshoppers caged on

untreated leaves had no mortality, while both species

caged on treated leaves showed equal mortality.

Conclusions

Grasshoppers in this study spent only a small portion of

their time feeding. They fed in sessions interspersed with

rest or movement (see table II.13–1.) Grasshopper spe-

cies that were easily controlled with baits fed on plant lit-

ter and detrital material on the ground and were therefore

the soil surface will remain available to ground-feeding

species.

Attracting grasshoppers that feed on live tissue to bait

and positioning bait in the known feeding locations are

some areas for the next stage of research.

Table II.13–1—Summary of feeding behaviors for six species of grasshoppers

Percent of time engaged in: Total

Species Basking Moving Feeding hours

Ageneotettix deorum 81.8 13.9 4.4 14.9

Aulocara elliotti 69.5 17.2 13.2 25.5