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Ornamentals and Turf |
Japanese beetle adults are now active in central North Carolina (i.e., my yard). There are a few things to consider when suggesting a control program. As you are probably tired of hearing, traps are not recommended since they may bring in more beetles than they kill. In many cases, hand picking (drop the beetles into a jar of soapy water or alcohol to kill them) and living with the defoliation is the best choice. Neem oil may act as a repellent and can be used to protect plants. Trees such as ornamental cherry and crabapple that have also been attacked by borers should be protected with foliar applications of Sevin for Japanese beetle control to help them stay healthy enough to defend themselves against the borers. Consider replacing these trees with alternatives that are less susceptible to insect attack.
While you are trying to decide whether you prefer paper or plastic bags, go ahead and make a decision to treat for bagworms, especially on those evergreens like Leyland Cypress. Bagworms are now large enough to notice, and small enough that they have not eaten much, yet! Bagworms have a wide host range; however, in landscapes they are usually associated with arborvitae, cedars or junipers. Heavy populations can do considerable defoliation. In spring, the newly-hatched caterpillars spin down from bags on silken threads and are blown about by the wind. Upon reaching a suitable host, the tiny caterpillar begins to spin its bag and as it grows it incorporates some of the host plant foliage into the bag for camouflage. Once a bagworm population takes hold, it can sweep through the plants quickly. Many vacationers return home to find a tree almost stripped. Plants such as Leyland cypress do not recover well from severe defoliation. You will not hear much about these insects from your clientele now, but you will hear about them later when the bags are large and the trees are bare.
Treating bagworms with insecticide while they are small is the most effective time for control. Hand-picking bagworms, when practical, is a safe and effective means of control. Bagworms are still small enough to be barely noticeable and still eating small bites. The situation will be different next month. Ornamentals and Turf Insect Information Note No. 81 provides information on the biology and control of bagworms. The population seems to be about two weeks ahead of last year.
Often mislabeled as bagworms by the general public, we have had two substantial reports of fall webworms this week. This is several weeks ahead of last year. Because fall webworm damage accrues over the summer, they usually cause little long-term health damage to the trees they defoliate. At any one location, the populations of fall webworms wax and wane so that they are conspicuous and damaging for a year or two and then the populations seem to disappear. Fall webworms feed on over 600 kinds of trees, shrubs and other plants. In North Carolina they seem to prefer pecans, persimmons, sourwoods and willows. The web starts at the branch tips and becomes enlarged to encompass fresh, green leaves until the web may become two to three feet long. Small trees infested with several broods of caterpillars may be entirely enclosed in webs. After feeding for four or five weeks, the caterpillars crawl down, spin cocoons and pupate in mulch or soil.
There are two or three generations of fall webworms each year in North Carolina, depending upon how early or late in the spring the first race emerges. White fall webworm moths (some moths have small black spots) emerge to mate and lay 350 to 900 eggs on the lower leaf surface. The hairy caterpillars spin the webs as they feed. Fall webworms can be destroyed by pulling down the webs and destroying the caterpillars if the webs are in reach of a pole. If the webs are within reach of a hose-end sprayer, several insecticides can be sprayed for control. Insecticides work best when the caterpillars are young, so it is best to treat as soon as the webs are first noticed. A product containing Bacillus thuringiensis or carbaryl is appropriate for homeowner use, while commercial applicators can use B.t. (e.g., Dipel) or Conserve. Talstar or Orthene (not for residential use) are two more of several other options.
Out with the old and in with the new. This week the tell-tale exuvium shell of the larger, green annual cicada was spotted on a tree bole at the North Carolina State University campus. We only mention this for your information. These cute critters are fewer and farther between than their annual counterparts that have been responsible for all the media attention this year. Their life cycle is about four years and not synchronized with each other. They do not make good pets, but they make good food for cicada killer wasps which will be along soon.
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 June 14, 2004 by Stephen J. Toth, Jr.
