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Leafhoppers
Nature Bulletin No. 566-A may 10, 1975
Forest Preserve District of Cook County
George W. Dunne, President
Roland F. Eisenbeis, Supt. of Conservation
LEAFHOPPERS
Many of us are blind to the common things about our feet Leafhoppers,
for instance. They are very small and expert at playing hide-and-seek
among plants, or they hop so quickly that the eye can scarcely follow
them. Yet, sometimes, in a patch of tall bluegrass, swarms of them
scatter right and left beneath our trampling feet. Sweep a butterfly net
over any summer meadow and you are likely to collect more
leafhoppers than any other insect. On hot summer nights, if reading in
bed is one of your pleasures, they come through window screens,
cluster about your reading light, and an occasional one stabs you with
its beak.
The leafhoppers are small, slender, torpedo-shaped bugs with piercing
mouth parts suited for sucking plant juices, their only food. They have
large eyes set in broadly curved or triangular heads; and, at rest, adults
hold their front wings roof-like over the body. About 2000 species are
known in North America Commonly less than one-eighth of an inch
long, they rarely reach a half-inch in length. Among the largest are the
Blue Dodger which feeds on okra or sunflowers, and the gaudily
decorated Red-banded Leafhopper which attacks a long list of garden
flowers and ornamental shrubs. The name "dodger" comes from their
habit of sidling around plant stems to conceal themselves. Some are
called "sharpshooters" because, when feeding actively, they pop out
droplets of unabsorbed plant sap, or honeydew. This sweetish liquid is
eagerly lapped up by ants, bees, wasps and flies.
Typically, their tiny eggs are laid in the leaves or stalks of plants. The
newly-hatched young, or nymphs, resemble small editions of the
parents. As they feed and grow, these molt their skins 4 or 5 times,
finally emerging as mature adults with two pairs of wings. One
generation a year is usual, but a few have two or three. Some species
hibernate as adults; others as eggs.
Leafhoppers are best known for the damage that a few of them do to
garden and farm crops, cultivated flowers, ornamental shrubs, and trees.
Their feeding may drain plant juices from the leaves causing them to
whiten, curl, wilt and die around the edges; or they stunt a plant by
injuring the green growing tips of the stems. Common instances of this
direct damage are found on apple trees, roses, potatoes, and alfalfa.
Far
more deadly to plants than the leafhoppers themselves are the
diseases that some of them spread. The beet leafhopper, for example, is
the only known carrier of "curly top, " an extremely destructive virus
disease of sugar beets, beans, tomatoes, spinach, melons and other
crops in our western states. The insect normally breeds on salt bush,
Russian thistle, greasewood and other weeds of arid foothills and desert
regions. Wintering on these wild plants, the adults lay their eggs in
March. This generation matures in May and June and flies in swarms,
often carried by the wind for hundreds of miles, to their summer hosts
where they produce a second brood and infect beet fields with the curly
top disease.
Two killing diseases, both insect-borne, are wreaking havoc among our
elms in the Middle West. Within the past few years, these two
epidemics have destroyed half of the elms in several down-state Illinois
cities and rural regions. The Dutch elm disease, most deadly and rapidly
spreading, is caused by a fungus carried from infected to healthy trees
by elm bark beetles. The other killer is elm phloem necrosis, a virus
disease spread entirely by the feeding of the elm leafhopper.
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Update: June 2012
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