in the Field and Garden
Barb Ogg, Ph.D., and Don Janssen, Extension Educators
can be serious pests of field and garden crops. Biblical accounts
of swarming "locusts" described the natural devastation that
grasshoppers can inflict on human civilizations. In more modern
times, grasshopper outbreaks have occurred in the Great Plains
in the 1870's, 1930's and 1950's, coinciding with droughty
North America, there are several grasshopper species that
defoliate field crops and garden produce as well as trees
and shrubs. Grasshopper injury to plants consists primarily
of leaf feeding; however, grasshoppers also feed on stems,
blossoms, ripening seeds and fruits. During heavy outbreaks,
hoppers may feed down to the crown of perennial plants, damaging
them beyond recovery. Four grasshopper species--the migratory,
differential, two-striped and red-legged cause about 90 percent
of the total damage to cultivated crops. Another 25 species
cause extensive damage to rangeland.
Cycle. Grasshoppers have three life stages--egg, nymph
and adult. In the most destructive grasshopper species, the
egg is the overwintering stage. The female grasshopper lays
from 8-25 egg pods, each containing 20-100 eggs. These egg
pods are laid in the soil, often in range, pasture or other
grassy areas that are not tilled. Because egg pods are susceptible
to fungal diseases favored by wet soil, survival of eggs is
best during dry years. Outbreaks are often related to periods
nymphs start feeding within one day after eggs hatch and usually
feed on the same plants as adults. Eggs hatch during late
May through July and the tiny nymphs may feed for several
weeks before they are noticed. The immature stage is vulnerable
to weather conditions, disease, predators, parasites and insecticides.
years, climatic conditions and biological controls act together
to reduce populations of grasshoppers so they cause minimal
damage to crops and garden plants. Many plants will withstand
minor grasshopper feeding, but when climatic conditions and
biological controls do not control grasshopper populations,
severe damage can result and control may be necessary.
When the density of grasshoppers is very high, there may be
a shortage of food and small grasshoppers will migrate to
find food. Likewise, adult grasshoppers are winged and may
migrate by flight to find food if it is in short supply. Grasses
are thought to be the normal food of grasshoppers; still,
migrating grasshoppers feed on nearly any kind of vegetation
and may destroy every green plant in their path.
Enemies. There are several important natural enemies that
help control grasshopper populations. These include blister
beetles, ground beetles and several parasitic flies. Many
species of birds and mammals also feed on grasshoppers.
Control in Field Crops.
are easiest to control when they are small and confined to
weedy areas like grassy terraces, fence rows and roadside
ditches. Use insecticide sprays or baits. Economic thresholds
have been developed for several crops.
Threshold: Consider an insecticide treatment when there
are 21-40 hoppers per square yard in field margins or waste
areas or 8-14 per square yard in the crop.
Insecticides Registered for Grasshopper Control of Field Crops:
(Furadan®) - corn, alfalfa, soybeans, wheat
(Lorsban®, Dursban®) - alfalfa, corn, soybeans
(Cygon®) - alfalfa, corn, soybeans, wheat
(Asana®) - alfalfa, corn, soybeans
(Penncap-M®) - alfalfa, corn, soybeans, wheat
(Orthene®) - alfalfa, soybeans
(Sevin®) - alfalfa, corn, soybeans, wheat
- soybeans, wheat
(Pydrin®) - soybeans
in Ornamentals, Turf and the Garden.
can attack ornamentals, and turf and garden crops crops--particularly
after field crops have matured. The best management strategy
is to control them when they are small in
margin and waste areas. The following insecticides are registered
for grasshopper control on some ornamental and turf crops.
Read the label to make sure the insecticide you have selected
can be safely used on any plants you are spraying.
SL; Sevin 6.3 G; Sevin 4% +; Chipco Sevimol®
for more information on Grasshoppers