 |
Ornamentals and Turf |
Tent caterpillars have hatched and can be seen making webs in the branch crotches of cherry, crabapple, and similar trees. The caterpillars leave the web during the day to feed on leaves and return in the evening. Simple physical destruction of the webs (without the use of fire) is effective but should be done in the early morning or evening when the caterpillars are present. A trick for those who are averse to touching the insects is to cover your hand with a plastic bag, scoop the web into the bag, and then turn it inside out and tie it shut. Pesticides may also be used on small caterpillars. Spray the foliage, not the webbing. Remember, this is NOT the fall webworm that occurs later in the year. Ornamental and Turf Insect Note No. 61 has more information and pictures.
Asian ambrosia beetle activity began about three weeks ago in the Coastal Plain of North Carolina. Ornamentals and Turf Insect Note No. 111 contains images of this insect and management information. Any permethrin insecticide products used on nursery plants must be so labeled.
The development of both insects and plants in the spring is regulated by temperature. Starting over 20 years ago, entomologists began to study this relationship as a way to predict insect activity. Observations over many years have shown that this relationship is consistent from year to year. Dan Herms of Ohio State has published his results based on six years of observation. This technique is easier to use than growing degree-days and incorporates a wide range of ornamental plants and pests. Some examples include when Cornus florida is at 50% bloom boxwood psyllids are emerging, and at 95% bloom birch leafminers emerge. When Cornus kousa is at first bloom holly leafminers are emerging and at 50% bloom euonymus scale eggs are hatching. We will be evaluating this technique in North Carolina landscapes over the next few years. Boxwood psyllids cause the cupped leaves at the terminal shoots. Any chemical controls for boxwood leafminers should work for boxwood psyllids.
Species of periodical cicadas (Brood X) are emerging in central to western regions of North Carolina and it should be a fairly spectacular emergence in some locations. Periodical cicadas are sometimes incorrectly called locusts (true locusts are Old World grasshoppers). Periodical cicadas are all 1 to 1.5 inches long including the wings. The eyes, legs and margins of the wings are orange. Periodical cicadas sing and fly in spring whereas other species of cicadas usually sing and fly during the summer. After spending years in the soil, cicada nymphs dig their way to the surface (and sometimes even construct mud chimneys up to 3 inches tall). Usually, in May, the nymphs crawl to the trunk of a tree or some other object and cling there. Times will vary due to weather and soil temperatures. Soon the insect molts into the winged adult stage, leaving behind the cast skin. Adult males begin to sing with a shrill buzzing noise to attract females. After mating, females use their saw-like ovipositors to open slits in the bark of hardwood twigs and insert eggs in two rows. Damage by cicadas is caused by the tiny slits made during egg laying. Heavily-damaged twigs may die back. This is normally not a significant problem with large trees. After 6 or 7 weeks, the eggs hatch and tiny, ant-like first stage nymphs drop to the soil to burrow in for the next 13 to 17 years. (Annual cicadas may complete their life cycle in 2 to 3 years.) While in the soil, the nymphs feed on the roots of many kinds of trees, but do not cause noticeable damage. Farming and urbanization of suitable habitats has reduced the populations of many cicadas, and it is thought that some broods of periodical cicadas may be extinct.
In woodlands, around homes and in most landscapes, it is neither practical nor desirable to try to eliminate cicadas. However, landscapers, nurserymen and apple growers may want to protect valuable woody shrubs and small trees. Covering with a lightweight fabric can protect ornamental trees and shrubs that are small enough. For more information on these and other species of cicadas, see Ornamentals and Turf Insect Information Note No. 17 or visit the University of Michigan periodical cicada web site.
Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age or disability. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.
Last modified on April 19, 2004 by Stephen J. Toth, Jr.
