1. Female of the Periodical Cicada (order Homoptera, family Cicadidae) ovipositing in the twig of a hardwood tree. The female cuts slits in the twig and lays her eggs in the slits. The eggs hatch and the nymphs drop to the soil where they burrow down to the roots and begin feeding. They use their piercing-sucking mouthparts to suck nutrients from the roots. Neither the nymphs or adults feed on the twigs, the only damage to them is from the act of oviposition. However, the twigs commonly die as a result of the oviposition damage.
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2. This slide shows a mass of spittle produced by the pine spittle bug. These masses consist of air bubbles and partially digested sap. It is excreted from the anus and glands on the abdominal segments. The mass covers the insect and provides a moist environment and protects the nymph from predators and desiccation. Adults do not produce spittle produced by that
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3. The spittle has been partially removed to show the Spittlebugs
nymphs that are feeding on the pine shoot.
4. The Saratoga Spittlebug is found throughout the eastern United states, and southern Canada. It is a pest of numerous pine species. They can cause serious damage in pine plantations that are 1-5 meters tall. Heavy feeding damage causes branch mortality, top-kill, stem deformity;, growth loss and tree mortality. They are economically important problems on red pine and jack pine plantations in the Great Lake States.
5. Many species of leafhoppers
feed on trees and shrubs but few are known to cause serious damage. There may be white
stippling on the foliage and browning and curling of foliage as a result of feeding. Many
leafhoppers are vectors of plant diseases and are common problems in cultivated crops for
that reason. The only important leafhopper vector of disease in trees is the whitebanded
leafhopper which is a vector of elm phloem necrosis, a virus disease of American elm.
6. Adult psyllids (Order Homoptera, family Psyllidae) resemble tiny, 1-5 mm., cicadas
or aphids. Unlike aphids they have strong legs and bodies adapted for jumping. They are
sometimes called jumping plant lice. Psyllids feed on plants with their piercing-sucking
mouthparts and some cause abnormal plant growths called galls. This picture illustrates
one type of psyllid gall, the hackberry
nipple gall caused by Pachypsylla celtidisgemma.
7. Here a hackberry nipple gall has been opened to shown the immature nymph of
the psyllid which lives and feeds inside the gall.
8. Aphids are small (1-6 mm), soft bodied, gregarious insects that suck sap from
leaves, stems or roots of many plant species. The white pine
aphid (Cinera strobi) shown here on a pine branch occurs in the eastern
United States. It has been known to kill young trees and branches of large trees. Other
species of Cinara attack juniper, cypress and various species of pines.
9. Aphids have complex life cycles and a single species may go have various
morphological forms. Here you can see both winged and
wingless forms of one species. Note the distinctive cornicles protruding from the end of
the abdomen, like tiny dual exhaust pipes.
10. The woolly alder aphid (Paraprociphilus tesselatus) shown here on
maple is a common species in the south. The production of the white waxy filament that
protects the aphid is the most distinctive sign of its presence on an infested plant. Two
hosts, alder and maple, are required for the insect to complete its life cycle.
11. Many aphid species cause galls on their host plants. These insects, and some other
groups, are able to redirect plant growth into abnormal structures. The gall former lives
and feeds inside the gall, protected from its enemies. This vagabond gall
caused by the aphid, Mordwilkoja vagabunda occurs on poplar.
12. The elm cockscomb gall aphid, shown here is
caused by Colopha ulmicola. It is a fairly common sight here in Alabama. The aphids live
inside the "comb".
13. Adelgids are close relatives of aphids (in the past they were considered aphids)
but they differ in that they are only found on conifers, they only lay eggs (they do not
give birth to active young as do aphids) and they have no cornicles. Some species have a
waxy coating and are called woolly adelgids. One economically important species is the
Hemlock woolly adelgid, Adelges tsugae
shown here.
14. The balsam woolly adelgid Adelges picae
is a serious pest of balsam in the northeastern United States, eastern Canada and the
southeastern U.S. It attacks several species of fir. The insect causes damage in two ways,
first by withdrawing plant sap and second, by injecting saliva that disrupts normal plant
growth. Heavy infestations has resulted in complete stand mortality, timber losses,
reduced tree growth and reduction in viable seed.
15. Mortality caused by the balsam woolly
adelgid on subalpine fir.
16. Heavy infestation of the balsam woolly adelgid on the bole on
Silver fir Abies alba. Bole infestations causes the production of compression
wood with poor conduction qualities.
17. Infestations of the balsam woolly adelgid on shoots
causes gouging of twigs and other signs of abnormal growth. Such unusual growth is the
result of the injection of insect saliva which contains chemicals that have plant growth
promoting properties.
18. Some species of Adelgids cause galls. These abnormal growths have a very defined shape, and sometimes size, that is specific to the species. This spruce gall, caused by Adelges cooleyi, results from the injection of growth promoting saliva. The gall kills the growing tip, much like damage caused by tip moths. These gall formers do not usually cause significant damage to forest trees but they can reduce the value of trees raised for Christmas trees or those used for landscape purposes.
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19. Scale insects are generally small, less than 10 mm). They are very diverse in form
and most people do not recognize them as insects. Scale insects secret a waxy covering
over their body that protects them from natural enemies and insecticides. They are among
the most destructive agents on ornamental shrubs and trees.
The cottony maple scale Pulvinaria inumerabilis, is one of the soft scales. This scale is an important pest of maples but is also found on apple, ash, linden, locust, willow, aspen, alder and many other shade trees. Infestations may be noticed because of the cottony covering of the scale, the honey dew that the insect produces or the sooty mold that grows on the honey dew.
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Direct questions or comments to: enebasa@auburn.edu
