Tree Care for Bugs in Las Vegas

Elm Leaf Beetles

• Elm leaf beetles, as their name suggests, attack various species of elm tree. Adults are elongated and greenish yellow with two black stripes down the center of their wing covers and black wing margins. Larvae are dirty yellow with two dark bands along their sides and small dark spots along their backs. Both adults and larvae feed on elm leaves. Larvae eat only leaf tissue, leaving behind veins. Adults consume the entire leaf. Damage by elm leaf beetles, as well as by other leaf-feeding pests, is rarely fatal to the tree, and control is generally not warranted. Successive defoliation over the coarse of several years can weaken trees, however. If you feel control is necessary, foliar sprays containing the bacterium Bacillus thuringiensis (Bt) "Tenebrons" or "San Diego" only target grubs and are safe for use around people and pets. Various strains of Bt are available for controlling other grub and caterpillar pests.

Aphids

• Using piercing, needlelike mouth parts, aphids suck the sap from leaves, twigs and buds. They are soft bodied, pear shaped and range in color from green, yellow and pink to brown, orange and black. Some species of aphids are covered in white, waxy filaments and look like tiny tufts of cotton. Feeding damage results in curled or deformed leaves and flowers. Aphids are not typically life threatening to trees, but they can be a nuisance for homeowners. They excrete a sticky substance called honeydew that drops from trees and can coat driveways, sidewalks, cars, furniture and buildings. Sooty mold, a powdery black mildew, feeds on honeydew and can adversely affect trees. Sooty mold coats leaves, shading them out, preventing photosynthesis and weakening the tree. Aphids are easily dislodged from trees with a strong jet of water from a hose. They cannot fly or climb and will die on the ground.

Mites

• Mites are arachnids and are closely related to spiders. Spider mites are very tiny and are often difficult to see. They use piercing mouth parts to suck sap from leaves, buds and fruit, causing yellowing, drying and bronzing. Some species of spider mites leave a fine webbing on plants and trees as they feed. These tiny pests thrive in dusty, dry conditions. Ensure your trees are well watered and are not suffering from drought stress. Wash spider mites off trees with a strong jet of water from the hose. Hosing your trees down can also keep them free of dust, reducing the chance of reinfestation.

  Eriophyid mites are also very small and feed on sap. They burrow into plant tissue to feed and lay eggs. In response to the damage caused by these mites, trees begin to manufacture extra tissue, called a gall. This extra tissue generally looks like a knotty, raised bump that grows and changes color with age. Galls can be found on twigs, leaves, branches, buds, flowers and fruit. They may be unsightly, but galls do not harm the tree. Prune them out if they bother you, but control is not necessary.

Tips for Keeping Trees Healthy

• Healthy trees are less likely to be attacked by insects and mites. If they do become infested, healthy trees are able to outgrow damage and generally are not severely affected. In desert climates like Las Vegas, irrigation is critical for tree health. Irrigate deeply and slowly to promote root growth. Lay your hose at the base of the tree, and let the water run for an hour or two. Of course, not all trees require the same amount of irrigation. Keep your tree properly fertilized for its size and type. Regular pruning promotes airflow and light penetration, reducing the risk of disease and opening up the canopy to predators, like birds, that might feed on pests.