Hibiscus (Hibiscus)


Leaf Feeders

Japanese beetles
Lee Townsend, University of Kentucky
Japanese beetles can feed on about 300 species of plants ranging from roses to poison ivy but basswood is one of their favorites. They usually feed in groups, starting at the top of the tree and working downward, and prefer plants that are exposed to direct sunlight. A single beetle does not eat much; it is group feeding by many beetles that causes severe damage. Adults feed on the upper surface of foliage, chewing out tissue between the veins. This gives the leaf a characteristic skeletonized appearance. For more information, see Entfact 451.

thrips
Alton N. Sparks, Jr., University of Georgia, Bugwood.org
Thrips are very small, elongate insects that feed by puncturing the outer skin of the leaf and sucking out the fleshy leaf tissue. Their feeding causes off-colored foliage and stunted growth.

 


Sap Feeders

Aphids
John A. Weidhass, Virginia Polytechnic Institute and State University, Bugwood.org
Aphids are soft-bodied insects that use their piercing sucking mouthparts to feed on plant sap. They usually occur in colonies on the undersides of tender terminal growth in the spring. Heavily-infested leaves can wilt or turn yellow and senesce prematurely because of excessive sap removal. While the plant may look bad, aphid feeding generally will not seriously harm healthy, established trees.

Some plants are very sensitive to feeding by certain aphid species. Saliva injected into plants by these aphids may cause leaves to pucker or to become severely distorted, even if only a few aphids are present.Also, aphid feeding on flower buds and fruit can cause malformed flowers or fruit.

Aphids produce large amounts of a sugary liquid waste called "honeydew". The honeydew that drops from these insects can spot the windows and finish of cars parked under infested trees. A fungus called sooty mold can grow on honeydew deposits that accumulate on leaves and branches, turning them black. The appearance of sooty mold on plants may be the first time that an aphid infestation is noticed. The drops can attract other insects such as ants, flies, and wasps that will feed on the sticky deposits. For more information, see Entfact 103.


San Jose scale
United States National Collection of Scale Insects Photographs,
USDA Agricultural Research Service, Bugwood.org
San Jose scale is one of the most destructive scale species. Infested stems, twigs or branches may be killed and heavily infested trees may die. These small circular brown armored scales have a series of dark concentric rings on their waxy covering. There are several generations each year. First crawlers are active from late May to early June, a second generation appears in late July and a third in late summer or early fall. Heavily infested plants may have a crusty covering of scales.

 


Borers

twig pruner larvae
James Solomon, USDA Forest Service, Bugwood.org
Twig pruners are the larvae of small beetles that tunnel in twigs and small branches. Female beetles lay their eggs about the time of bud break in the spring. Eggs are laid in small holes which are chewed into the bark. The larvae that hatch from these eggs bore into and tunnel toward the base of twigs. In late summer, they chew concentric circles outward toward the bark then move toward the tip. The twig eventually snaps and falls to the ground. The larva pupates in the fallen twig and emerges as an adult in the spring. Collecting and destroying fallen twigs can help to reduce infestations.

 


Galls

Phylloxera leaf galls
Whitney Cranshaw, Colorado State University, Bugwood.org
Phylloxera galls are up to 5/8 inch long hollow green growths caused by aphid-like insects called phylloxera. The insect spends the winter as an egg inside a dead female in bark crevices and cracks or in old galls. The eggs hatch as leaf buds expand and the small phylloxera nymphs crawl to leaf buds and begin to feed on sap from the tender tissue. Resulting stem galls distort leaf growth and ultimately cause premature leaf drop but the damage is only cosmetic. A dormant oil spray during the winter may reduce infestations.

 

website content by L. Townsend and J. Larson  website design by P. Dillon   copyright © 2017 - University of Kentucky Department of Entomology
University of Kentucky College of Agriculture | S-225 Agricultural Science Center North, Lexington, KY 40546-0091 | 859.257.7450
An Equal Opportunity University | Last modified 02/20/2020