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Grasshoppers
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Grasshoppers |
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Identifying and Controlling Grasshoppers
General information plus a brief review of the four most destructive grasshoppersNote: The following information has been compiled from
40 years professional experience, agronomy textbooks, entomology literature
and university extension service websites.
While there are some differences in the seasonal characteristics of grasshoppers, that is, the timing of the egg hatch and the time it takes to complete their growth development, all grasshoppers commonly have three life stages… it begins with the hatching from an egg, then they go through 5-6 nymph stages ultimately to become a winged adult (a process of development called an ‘incomplete metamorphosis’). The nymphs, like the adults, are active feeders and the stages of nymph development occur over a 35-50 day period. In addition, practically all grasshoppers over-winter underground in the egg stage. In the fall, a typical female will lay a cluster of 20-100 eggs at a time on 8-25 different occasions and each cluster is called a 'pod' (egg case). A grasshopper egg pod is pictured on the left. This pod is actually just soil particles surrounding the egg mass due to a glue-like secretion by the female. It apparently serves as a protective shield. These banana-shaped pods, about 1 inch long, are the result of eggs having been laid in the soil about ½ to 2" deep. The eggs will begin developing in the spring when temperatures reach 50-55° F… although, depending on the species, it could be anytime from early spring to early summer. Late summer hatches are 2nd generation hatches but not all grasshoppers have two generations within a single season. Upon emerging from the egg, these first instar nymphs (and successive instar
nymphs) will resemble adults except for being smaller. Their growth occurs in a
series of episodes called molting, the shedding of skin whereupon after each
incidence the grasshopper becomes bigger. Each progressive stage of nymph
development is referred to as an 'instar' (i.e. 2nd instar grasshopper, 4th instar
grasshopper). The final molting will result in a full-size adult with wings. While grasshoppers are known to feed on just about any type of vegetation,
they are also known as being somewhat particular and will target a certain type
of plant among other plants. They are noted to have a preference for grass,
which would include small grains such as wheat, barley and oats, but also have a
tendency to attack legumes and vegetables, more specifically alfalfa, beans,
corn, lettuce and potatoes. Grasshoppers can be found anytime during the spring
and summer but are most numerous in the fall. Depending on their numbers, damage
can be significant as entire plants can be stripped of vegetation. Grasshoppers
prefer the younger plants, the most tender of leaves generally, but will also
feed on stems, blossoms and fruit. Winged adults will migrate in search of a new
food source when necessary. Grasshoppers have a season-long lifespan and will
continue to feed until cold temperatures eventually kill them. Some species can
produce a 2nd generation within a season which can pose a threat to fall-planted
winter wheat. A.O. Kime - former Arizona and California agricultural Pest Control Advisor (1970-1992) and family farmer (1973-1998)
differential grasshopperMelanoplus differentialis Aside from grasses and small grains, the differential grasshopper is particularly noted for being a plant pest of alfalfa, corn, cotton, soybeans, vegetables (various), and deciduous fruit trees. It is a very large grasshopper (1½ - 2") and is more prominent between the rocky mountains and the Mississippi River. It has been noted as most injurious in the Great Plains, the upper Mississippi Valley and southern states. Typically, they'll move from one crop to another and often competes with the twostriped grasshopper for dominance. One generation per year. For further information and photographs, click the image (external USDA link).
Host weeds: ragweed, sunflowers and prickly lettuce (in lieu of these, likely any available weed) Predators: (same for all grasshoppers) bats, blister beetles, ground beetles, parasitic flies, frogs, lizards, praying mantis, raccoons, rodents (chipmunks/squirrels), snakes and birds (crows, mockingbirds and sparrows). Preying on the younger grasshopper nymphs could also include ants, centipedes, crickets, dragonflies, spiders and yellow jackets.
twostriped grasshopperMelanoplus bivittatus Aside from grasses, the twostriped grasshopper is most associated with small grains, alfalfa and corn although in urban areas it is noted as a damaging pest of flowers and garden vegetables. It, like the differential grasshopper, is very large (1½ - 2") and is often equally as prominent. In Kentucky, however, they have been noted as being "little more than 1 inch long". They also feed on dry plant parts (litter) on the ground (somewhat unusual for a grasshopper). One generation per year. For further information and photographs, click the image (external USDA link).
Host weeds: mustards, ragweed, sunflower, sowthistle, kochia, prickly lettuce but most any weed growing on ditch banks and along roadsides and crop borders plus they will reside within wet meadows and tall prairie grass. Predators: (same for all grasshoppers) bats, blister beetles, ground beetles, parasitic flies, frogs, lizards, praying mantis, raccoons, rodents (chipmunks/squirrels), snakes and birds (crows, mockingbirds and sparrows). Preying on the younger grasshopper nymphs could also include ants, centipedes, crickets, dragonflies, spiders and yellow jackets.
migratory grasshopperMelanoplus sanguinipes The migratory grasshopper is known to commonly inhabit grasslands and meadows, but typically, it also poses a danger to croplands... whatever is available. It is considered, although certainly not unanimously, to be the most destructive of all grasshopper species. Aside from spawning its bad reputation, perhaps the damaging episodes (swarms) during the 1930s and 40s helped promote this belief. Whether it is the most damaging grasshopper is undoubtedly a regional matter. It is most noted for its damage to small grains and rangeland grasses... also fall-planted winter wheat is prone to damage from its 2nd generation hatch. For further information and photographs, click the image (external USDA link).
Host weeds: dandelions, downy brome, Kentucky bluegrass, mustard, pepperweed, ragweed and winter-planted barley and wheat (or volunteer barley and wheat). Predators: (same for all grasshoppers) bats, blister beetles, ground beetles, parasitic flies, frogs, lizards, praying mantis, raccoons, rodents (chipmunks/squirrels), snakes and birds (crows, mockingbirds and sparrows). Preying on the younger grasshopper nymphs could also include ants, centipedes, crickets, dragonflies, spiders and yellow jackets.
Redlegged GrasshopperMelanoplus femurrubrum The redlegged grasshopper is a medium-sized grasshopper and the most prominent species in the eastern United States and Canada. Aside from being damaging to small grains, alfalfa, clover and soybeans, it is known to cause damage in corn, beans, beets, cabbage, potatoes and tobacco. Two generations can occur and a partial third in Florida. For further information and photographs, click the image (external USDA link).
Predators: (same for all grasshoppers) bats, blister beetles, ground beetles, parasitic flies, frogs, lizards, praying mantis, raccoons, rodents (chipmunks/squirrels), snakes and birds (crows, mockingbirds and sparrows). Preying on the younger grasshopper nymphs could also include ants, centipedes, crickets, dragonflies, spiders and yellow jackets. Summary: In researching the differences in the above four (4) grasshopper species, there was a common reoccurring theme.... while a particular species of grasshopper may have host preferences, in lieu of those, it will attack most any crop. All grasshoppers, in other words, are opportunists. The effective difference is from the amount of damage caused and that, in turn, is due to their distribution and prevalent numbers. Any grasshopper, in sufficient numbers in a certain location, would likely cause an equal amount of damage as would any other grasshopper equally advantaged. The greatest difference is perhaps their over-wintering survival rates. Credits: Clicking on any thumbnail image above will take you to the photograph source (another website). The 9th U.S. Circuit Court of Appeals has ruled that a thumbnail image is ‘fair use’ provided it contains a hyperlink to the webpage where the full-size photograph was obtained, Nonetheless, if any owner of the copyright objects to our usage, upon notification we will immediately withdraw the thumbnail image.
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