Tree & Shrub Insects
Looking for information on a specific insect? Below you will see links to each of the insects covered here.
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Ambrosia Beetles Aphids Bagworms Japanese Beetles Lacebugs Leaf Miners |
Oakworms Scale Spider Mites Tent Caterpillars Whiteflies |
| Ambrosia Beetles: Ambrosia beetles bore inside and feed on fleshy tissue under the bark surface of trees. The external signs of ambrosia beetles are small piles of white boring dust on the surface of the target plant. The term "ambrosia" refers to the fungus that the insect carries with it into the host plant. Growth of the fungus in the wood produces a black and gray stain surrounding the beetle tunnels. Removal of the affected plant is the best means of controlling damage done by ambrosia beetles. |
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| Aphids: Aphids are small (about 1/4 inch in length), soft bodied insects that may vary in color from green to yellow to black. Some species are winged during certain times of the year. Generally, aphids can be recognized by their cornicles, a pair of tube like structures projecting from the rear of their bodies. They are frequently found in large numbers clustered together in the backs of leaves or on the stems of new growth. Aphids suck the chlorophyll from plant material causing discoloration of foliage. Wooly Aphids feed in a similar fashion to other aphids, but these are best identified by the white waxy strands that surround them and the plant material on which they feed. |
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| Bagworms: Bagworms are caterpillars that live inside spindle shaped bags which they construct to protect themselves against birds and other enemies. The bags are made of silken threads and foliage, and they often times go unnoticed until damage begins to become evident on the host plant. Bagworms mainly feed on needled evergreens such as Leyland cypress, juniper, and arborvitaes. They are most active in the late summer. They can cause broad spread defoliation to host plants. The worms enter and exit the bag as they
feed. They continue to expand the bag as they grow larger. When they mature, female
bagworms lay as many as 1000 eggs in the bag. These eggs pass the winter in the bag, and
they emerge the next summer to feed, grow and reproduce. |
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| Japanese Beetles: Adult Japanese Beetles are 3/8-inch long metallic green beetles with copper-brown wing covers. Adults emerge from the ground and begin feeding on plants in June. Individual beetles live about 30-45 days. Activity is concentrated over a four to six week period, beginning in July, after which the beetles gradually die. They usually feed in groups, starting at the top of a plant and working downward. They prefer plants exposed to direct sunlight. Adults feed on the upper surface of foliage, chewing out tissue between leaf veins. This gives the leaf a characteristic skeletonized appearance. They tend to do little feeding on thick, tough leaves. |
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| Lacebugs: Lacebugs get their name from the appearance of the area behind their head and the wing covers. The area forms a lacelike covering over the body of the insect. They are 1/8 to 1/4 inch in length and are partially transparent. Lace bug damage appears on the upper leaf surface as white to yellow chlorotic spots and the lower leaf surfaces will be cluttered with black spots and the old cast skins of immature lacebugs. |
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| Leaf Miners: The adult forms of leaf miners are  small wasps or flies. These adults lay eggs on the undersides of broadleaf
evergreens and deciduous trees. The eggs hatch within a few weeks, and the larvae then
enter the leaf through the midrib.
The young pass the winter inside the leaves, and then begin to feed on the fleshy soft leaf tissue in the spring as they continue to mature. Although the leaf miners do not generally move from leaf to leaf, a heavy population of these insects can cause widespread aesthetic damage to the host plant. |
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| Oakworms: Extensive defoliation can occur to oak trees between May and September due to oakworm infestations. Young larvae chew all the way through the leaves, and cause a skeletonized look on oak trees. Oakworms mature to about one inch in length. They are best identified by the dark stripes running down the length of their bodies. The mature larvae molt into moths. |
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| Scale: Scale insects are small, soft-bodied insects that secrete a protective covering over their bodies. These coverings vary in color from white to red to black. Some are flattened while others are more turtle shaped. This covering protects the scale and makes control difficult. Scales insects are most easily controlled when insecticide applications are timed during their early development stages. |
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| Spider Mites: Spider mites are most often found on the backs of leaves and on the new growth of needled plants. They are so small they can barely be seen with the unaided eye. Adults are oval-shaped and have eight legs and no antennae or wings. Spider mites cause yellowing of leaf and needle material by sucking out the chlorophyll. |
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| Tent Caterpillars: Tent caterpillars are attractively colored larvae that reach about 1 1/2 inches in length. They have a few long hairs on their bodies, mostly along the sides. They are commonly seen in the early spring closely associated with the webs or "tents" they construct in the crotch of small limbs on their host plant. This tent serves as a refuge for the larvae during the night and during rainy weather. They have only one generation per year. |
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| Whiteflies: Whitefly adults resemble small gnats. They range in size from 1/10 to 1/16 of an inch and have four broad, delicate, milk white wings. The immature whiteflies are attached to the underside of leaves. They are oval, flattened and yellow to almost transparent. Whiteflies often occur in tremendous numbers. When a heavily infested plant is disturbed, the air is filled instantly with a white cloud of these insects.
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