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Leafhoppers
| Article
# : |
11070 |
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Section : |
NATURAL SCIENCE
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| Issue
Date : |
6 / 1986 |
578 Words |
| Author
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Gary F. Hevel
Gary F. Hevel is the collections manager for the Department of
Entomology at the Smithsonian Institution, Washington, D.C. |
Next time you walk across a field, watch closely and note that you are flushing leafhoppers as you move. Most of us have had contacts with leafhoppers without realizing it. Their populations in agricultural, garden, and natural habitats can be tremendous. It has been calculated that as many as a million leafhoppers can populate a single acre of grassland! Some kinds are capable of moving great distances from development centers. (The most unusual case involved tons of one species landing on remote, mid-Atlantic Ascension Island. Trade winds had apparently carried the insects from Angola, a distance of 2,000 miles.)
The majority of leafhopper species are about one-quarter inch in length, and are frequently green, yellow, or brown to match the colors of the foliage and stems which they inhabit. However, many others--especially in the tropics--display spectacular coloration and patterns.
Leafhoppers belong to the huge family Cicadellidae, of which some 15,000 species are named and described. However, it is expected that this number will triple, especially when tropical areas are more thoroughly surveyed. Some genera, such as Erythroneura, comprising about 1,000 species, are extremely complex and boggle the minds of specialists. Identification often requires comparisons of their minute genitalia under the microscope.
The majority of leafhoppers "stay put" on a particular host plant and move only when disturbed. Then, propelled by saltatorial legs, they hop away, taking wings as they go. If you slowly approach one or more leafhoppers you can see their method of feeding. Leafhoppers feed upon the juice of plants by the use of sucking mouth parts. However, they also depend on the sap pressure of plants to complement their own "pump." As sap pressures vary, they must deal with the problem of too much sap entering the body with consequent blood dilution and perhaps other physiological problems. The problems, however, are solved by a looping of the hindgut and associated excretory organs (Malpighian tubes) against the foregut, forming a "filter chamber." In this chamber excess sap takes a shortcut into the hindgut where it can be excreted from the body without the complication of passing through the midgut where most food assimilation takes place. The excreted plant sap, mixed with other undigested material, is popularly known as honeydew.
Honeydew accumulates on leaf surfaces and is eagerly sought as a diet-supplement by butterflies, flies, ants, and other insects. Cars parked under a tree infested with leafhoppers and related
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