Azalea (Rhododendron)

Leaf Feeders

Azalea caterpillar
Chris Evans, University of Illinois,
Azalea caterpillars have one generation each year during August and September. Small larvae skeletonize leaves, large larvae consume entire leaves. In sufficient numbers they can defoliate plantings in a short time. These hairy caterpillars have 7 light stripes along the body; its head and legs are red. Full-grown caterpillars are about 2 inches long. Azaleas are the preferred host but the caterpillars also feed on blueberry foliage.

Redheaded flea beetle
Brian Kunkel, University of Delaware,
Redheaded flea beetle adults are 1/4 inch long with a black body and red head (but it can be difficult to see). They have large femurs on their back legs that allow them to hop, as the name implies. Larvae are soil-based, have a creamy color and can be up to 1/2 inch long. This pest overwinters as eggs in the soil, and larvae hatch out to feed in the root zone, before pupating to emerge as adults. In Delaware and Maryland this first group of adults emerges when Southern magnolia is in bloom. A second generation occurs later in the summer. Adults feed on leaves causing extensive shot-hole damage.

Two-banded Japanese weevil
University of Georgia , University of Georgia,
Two-banded Japanese weevil adults are about 1/4 inch long and pear shaped. Unlike other weevils, which have long snouts, this weevil has a stout, short snout. Adults have a mottled appearance, with grey and brown blotches giving them an almost camouflage-like appearance. There are two distinct bands that form across the back of the elytra. Larvae look like other weevils -- small, white, and legless. The adults feed along the edges of leaves, making notches at first, then tattered edges. In heavy infestations, whole leaves may be consumed. They overwinter as eggs, larvae, and adults. Overwintering adults resume feeding in May and produce the next generation with new adults emerging in June-July.


Sap Feeders

Azalea lace bug adult
Pest and Diseases Image Library,
Azalea lace bugs are 1/8 to 3/16 inches long sap-feeding insects with clear, ornate, lacy wings; The immature stages (nymphs)are spiny and wingless. Adults and nymphs live on the lower surface of leaves. As they feed, they leave tiny yellow to white spots on leaves and dark, varnish-like waste spots on the under sides.

These lace bugs spend the winter as eggs inserted into leaves. The eggs hatch in early spring and the nymphs begin to feed on plant sap. Development from egg to adult takes about 5 weeks. There are several generations each season. Usually, there are only a few insects in the first generation so feeding symptoms are not noticed. Numbers and damage to plants increase to a peak in late summer. When abundant, feeding can make plants unsightly and may cause premature leaf drop.

Azalea lace bug damage

Azalea mealybug
United States National Collection of Scale Insects Photographs,
USDA Agricultural Research Service,
Azalea mealybugs produce cottony white sacs on twigs and in crotches of limbs. They produce large volumes of liquid waste that drops on lower limbs and branches. Black sooty mold will grow on these deposits.

Four-lined plant bug
Johnny N. Dell,
Four-lined plant bug adults are between 1/4-1/3 inch long, have an orange head and yellowish body with four black stripes running down the back. The nymphs are red to red-orange with black dots. There is one generation per year, with feeding and growing occurring in May and June. As they feed, four-lined plant bugs create circular brown-black spots. The spots are about 1/16-inch wide and can merge together to create a blotchy appearance that resembles a disease issue. The damaged spots can also dry and fall out of the surrounding healthy tissue, leaving a hole behind.

Southern red mite
Tracy Wootten, University of Delaware,
Southern red mites are tiny (1/50 inch) arthropods with a dark red or brown color. They live on the underside of leaves and use needle-like mouthparts to remove the contents of individual cells. This produces tiny white to yellow spots on leaves, sometimes called flecking or bronzing. Infestations are usually most serious during cool periods of spring and fall.

Greedy scale
United States National Collection of Scale Insects Photographs , USDA Agricultural Research Service,
Greedy scale are small armored scales that create a conical shaped cover. As they grow and shed their old exoskeleton, it is incorporated into the wax that makes up the shield. Eventually this results in a characteristic off-center nipple or dot on the outer coating. There are often concurrent overlapping generations on plants


Root Feeders

Black vine weevil grub and adult
grub: Peggy Greb, USDA Agricultural Research Service, ;
adult: Cheryl Moorehead,
Black vine weevil grubs are white legless larvae with yellow brown or red heads that live in the soil and feed on plant roots. Moderate root feeding may cause plants to show signs of drought stress. Girdling can occur and nutrient transmission is disrupted, occasionally leading to death of the plant. The adults (0.5 inch long) are dark snout beetles that may chew crescent-shaped holes in leaves while feeding at night. Normally there is one generation per year with the larva overwintering. Pupation and adult emergence occurs in the spring. Sometimes adults may overwinter which can result in damage occurring from larvae earlier in the season.


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