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ENTOMOLOGY: INSECT PESTS [continued]

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  MG Manual Reference
Ch. 3, pp. 29 - 33
[ Insect Pests: ipm | landscape; foliage, sap, trunk, root | turf grass; root, leaf, sap, nuisance | household; structures, living quarters, products | outdoor | citrus | fruits | gardens ]


PESTS OF LANDSCAPE PLANTS [continued]
SAP FEEDERS Top
Hemiptera

Cactus Bug
Cactus bugs are true bugs with sucking mouthparts. They are light yellow with a dark brown head, with a wide yellow stripe down the back of their head, and a darker triangle in the middle of the back. Females attach their eggs to the underside of cactus spines. Cactus bugs are introduced pests of Opuntia cactus. Their feeding causes yellowing of the pads and sometimes death of the plant.
Lacebug
Lacebug
Lacebugs Lacebugs are flattened insects, roughly rectangular in shape when viewed from above. They take their name from the lace-like expansions projecting from the thorax and front wings. Several species are found in Arizona. Adult females lay eggs near the leaf veins on the underside of leaves. Nymphs and adults suck sap from the underside of leaves of plants such as basswood, sycamore and lantana. They are also destructive to composites and annual flowers. The feeding damage looks similar to spider mites, except lacebugs often leave dark spots of excrement as well as causing yellow stippling.
Aphid
Aphid
Homoptera

Aphids
Aphids vary in color depending on the species and their host. Numbers can build up quickly because the adults are capable of producing live offspring without mating. They feed in groups, often on the growing tips of a plant. Aphids suck the juices from a plant, and the excess they excrete as a sticky material called honeydew. A black fungus known as sooty mold often grows in the honeydew, and if there is enough covering the leaves it may interfere with photosynthesis.
Cotton Aphid Nymph
Cotton Aphid Nymph
The arborvitae aphid is a brown species that infests arborvitae, Italian cypress and false cypress.
The cotton or melon aphid is dark green to black in color, and feeds on cotton, oranges, melons, poppy, chrysanthemum, cucumber, dogwood, begonia, milkweed, spinach, beets and many others.
Cotton Aphid Adult
Cotton Aphid Adult
The oleander aphid is a yellow-orange aphid with black cornicles found on oleander during the spring and on desert milkweed at other times. They rarely cause significant damage to either plant, and may actually be beneficial because they serve as food for biological control agents.
The rose aphid is a relatively large species which is either green or pinkish in color. It is commonly found on the unopened flower buds.
The rusty plum aphid is a rusty brown species found feeding on plum, corn, grasses and many wild flowers.
Aphids may be washed off with a garden hose, but be careful when temperatures are high because the water may cause leaf burn. If aphids persist, try spraying with a solution of up to two tablespoons of liquid detergent per gallon of water. Test a small number of leaves first, because some plants will be sensitive to soaps.
Cochineal Scale
Cochineal scales may be mistaken for mealybugs. The females are red in color with white waxy plates, which gives them a cottony appearance. The species in Arizona feeds on Opuntia (prickly pear) cactus. The insects may be brushed from the cacti, dried and their red color used as a dye.
Several insect predators control this scale, including several species of lady beetles, syrphid flies and lacewing larvae.
Leafhopper
Leafhopper
Leafhoppers
Leafhoppers are wedge-shaped insects, about 1/8 inch long with jumping legs. They are capable of strong flight. Some species may be serious pests. They suck the juices from the plant and excrete excess fluids in the form of honeydew. As with aphids, this sugary substance may support the growth of sooty molds.
Because they are so mobile, leafhoppers may be difficult to control. Floating row covers may be used to prevent leafhoppers from damaging gardens.
Whitefly Adult
Whitefly Adult
Whiteflies
Adults are less than 1/16 inch long and have a pale yellow body covered with a white waxy material. The sedentary, scale-like immatures suck sap from the under side of leaves. The species of whitefly that is currently the most significant pest becomes abundant in late summer and early fall. However, other species of whiteflies are found here, including greenhouse whiteflies, ash whiteflies and banded-wing whiteflies. These species may be abundant at different times of the year and require different control measures.
Whitefly Immatures
Whitefly Immatures
Control whiteflies by spraying the underside of leaves with a mixture of one teaspoon to two tablespoons of dish detergent per gallon of water. Test for toxicity to plants by starting at the lowest dose and gradually increasing the amount of dish detergent added. Spray every three to four days or as needed.
Spider Mites
Spider Mites
Class Arachnida

Spider Mites
Spider mites are tiny creatures, some less than 1/50 of an inch. Most are so small they can not be seen without the aid of a microscope. Mites are usually oval or rounded in shape, and may be yellow, red, greenish, or brownish in color. Spider mites get their name from the fact that they produce a fine webbing between leaves, a sign of infestation. They suck sap from leaves and fruit, which causes yellow spots or ÒstipplingÓ on the leaves. Their feeding may cause deformations such as twisting and stunting of leaves, as well. Other types of mites cause galls.
A mix of soap and water may be used to wash plant mites off leaves, as with whiteflies. Several biological control agents are also available for the control of spider mites.
TRUNK AND/OR LIMB FEEDERS
Flatheaded Borer Adult
Flatheaded Borer Adult
Coleoptera

Flatheaded Borers
Adult flatheaded borers are 1/2 to 3/4 inch long, often olive-gray to brown with a metallic gold, bronze or green cast to the fore wings. Some may be brightly colored. The larvae are cream-colored, legless grubs up to 1 1/2 inch long. The segment behind the head is greatly widened. Larvae burrow beneath the bark of shrubs and trees such as apple, ash, box elder, cherry, peach, pear, pecan, raspberry, and roses. They are usually host specific.
Flatheaded Borer Larva
Flatheaded borers invade most commonly where the trunk of trees or bark of shrubs has been sunburned or otherwise damaged. The best way to avoid infestations is to protect young plants from sunburn and keep older trees sound. Prune out infested material and destroy it. Insects that are hidden within the wood are not accessible to chemical sprays.
Ocotillo Borer
Related to the flatheaded borers that attack roses and apples, the ocotillo borer is a species that attacks only ocotillos. The adults lay eggs into the bark, and the legless larvae mine into the cambium, causing rapid decline of the plant. They seem to prefer plants which are stressed, particularly newly planted ocotillos.
Avoid planting new ocotillos during the summer, when adults are active. Cut any branches that do not leaf out below the leafless area and dispose of immediately (the beetles can survive in cut portions). If the plant does not leaf out in the spring, inspect for grubs and if present, dig it up and dispose of immediately.
Round-headed Borers
The adults are called long-horned beetles because their antennae are often as long as or longer than their body. Some may reach lengths of four or five inches.
Round-headed Borer
Round-headed Borer
One common species is the locust borer, which is black with yellow stripes, and mimics a wasp. The larvae bore in solid wood of plants such as apple, hickory, locust, mesquite and poplar. They are legless cream or white grubs which are uniform in width (the segment behind the head is not enlarged).
Borers generally attack weakened trees and shrubs. They may be prevented by keeping trees and shrubs in their best condition. An exception is the mesquite twig girdler, which girdles and kills small twigs of mesquite trees. The female beetle then lays an egg in the section that is killed and the immature develops within the wood.
Palo Verde Beetle
Palo Verde Beetle
ROOT FEEDERS Top
Coleoptera

Palo Verde Beetle
Immatures (grubs) feed on the roots of Mexican palo verde and other non-native trees, and are six inches long when mature. They spend up to three years underground. Adult beetles are four to six inches long with long antennae and a "collar" of spines on the thorax. They are active in July.
Currently there is little that can be done to control these beetles. They attack stressed trees, so the best prevention is to keep trees as healthy as possible.

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