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Ornamentals and Turf |
Fall webworms attack the ends of branches rather than the crotches of trees. They are not present in the spring as are the tent caterpillars. Some of their favorite plants are sourwoods, pecans and persimmons. Fall webworms have already been spotted hatching. Some entomologists feel that the early webworms are a separate subspecies of fall webworms. Because fall webworm damage accrues over the summer, fall webworms usually cause little long-term health damage to the trees they defoliate unless the trees are completely defoliated year after year. At any one location, the populations of fall webworms wax and wane. They are conspicuous and damaging for a year or two and then the populations seem to disappear. Most of the populations will be noticed later in the summer. They overwinter as pupae in cocoons in the leaf litter. White moths emerge to mate and lay 350 to 900 eggs on the lower leaf surface. The hairy caterpillars spin the webs as they feed. The best treatment is to prune or pull the webs from the tree as soon as they appear, if possible. Bacillus thuringiensis, Conserve, Orthene, or Sevin sprayed on the foliage closest to the webs should control the webworms.
The cicada killer wasp uses cicadas to provision its nest. Cicadas are caught and stung by the wasp, then dragged back to the nest. Once in the nest, the female wasp lays her eggs on the cicada. Soon wasp larvae hatch from the eggs and feed upon the cicada. When mature, the wasp larvae pupate and another generation of wasps emerges to carry on the life cycle. The cicada killer wasp is one of the most attractive-looking wasps, and the sight and sound of many wasps swarming in a yard is impressive. Although these wasps appear to be ferocious, I know of no one who has ever been stung by them even though the females have an impressive stinger (males do not sting). Control is usually not nearly as necessary as the homeowner thinks since the wasps represent little danger to humans. The active period only lasts a few weeks, anyway. Because they control cicadas, these wasps can be regarded as beneficial. Ornamentals and Turf Insect Information Note No. 63 provides additional information on the biology and control of cicada killer wasps. Populations may be low this year due to the dry, hard ground which affects cicada and wasp emergence.
First came the cicada, then the cicada killer wasp and now the velvet ant. One of the velvet ants is nick-named the cow killer because of its amazing stinger. This handsome insect squeaks audibly (especially when stepped on) and is exceptionally tough. However, the squeaks of the cow killer would hardly be heard over the painful screams, if the person stepping on the wasp were barefooted! Velvet ants are parasitic wasps. The females are wingless and resemble hairy ants. Female velvet ants seek out a host nest and lay their eggs on the host larva. The velvet ant larvae consume the host wasp larvae and pupate and mature into another generation of velvet ants. The cow killer parasitizes the nests of a large black, yellow, and orange-colored solitary wasp called the cicada killer. The cicada killer provisions its nest with cicadas that the cicada killer larvae eat. Cow killers slip into the host wasp nest, lay their eggs, and depart. The exceptionally tough exoskeleton of the cow killer protects it from stings of the host wasp in case they meet in the nest. Velvet ants are not usually numerous, and no control measures are usually needed. Usually a big stick or heavy-soled shoe will take care of this insect, but normally there is no harm in letting them live.
Magnolia scales and tuliptree scales are among our largest scale insects and are sometimes quite damaging to tulip trees and magnolias. Although they are in different genera, these scales are quite similar in appearance and biology. The biology is unusual in that these scales reproduce in late summer and the tiny new scales overwinter on the twigs and stems. (Most of the soft scale insect pests of ornamental plants reproduce in May or early June.) Male scales appear in early summer and mate with the females. The females swell considerably with eggs during the summer but the eggs hatch as they are laid so that it appears the crawlers are born rather than hatched. They have one generation per year. Numerous parasitic and predaceous insects (including a predaceous caterpillar) prey upon these scales! Infested trees may become sticky with honeydew excreted by the scales and black sooty mold fungi may grow in the honeydew. The tree may be weakened overall with sparse foliage and dead branches, or the trunks may be distorted because the scales have killed the leader branches over the years. Most homeowners object to the honeydew as well as the wasps, flies and bees that are attracted to the honeydew. If the tree is small enough to be sprayed with insecticide, the next few weeks would be a good time to spray as the nymphs are exposed on the stems. It is recommended that infested trees be sprayed with horticultural oil, Orthene, Sevin or Mavrik.
Halictid bees are also known as sweat bees. These bees are often companions of the landscaper on warm spring and summer days as the bees land on the arm or leg to lap perspiration. Sometimes these bees are caught in the fold of an elbow or knee and they sting with a slight but noticeable sting. When sweat bees are abundant, about the only thing to do is to wear long sleeves or use an insect repellant. Sweat bees are solitary bees and only primitively social. They do not have an organized alarm pheromone which encourages the bees to swarm out of the nest after a predator. Sweat bees nest in soil. The tiny nest resembles an ant hill (a hole in the ground surrounded by a small mound of loose soil called the tumulus). A very small amount of Sevin sprinkled on the hole would be fatal to these attractive, beneficial pollinators; however, peaceful coexistence is encouraged.
Green June beetles arrived June 27 with great fanfare after being held captive in the hard soil. Rainfall on June 26 softened turf enough for the large green beetles to emerge simultaneously around much of the state. These beetles are metallic green and four times the size of Japanese beetles (Japanese beetles may also be increasing in their presence since the rainfall).
Despite the buzzing around turf and pasture, green June beetles do little harm to plants and no harm to people. They can be handled without fear (if you want to impress your friends). Though there are possible control measures available for turf a little later in the season, I have rarely ever seen this justified in home turf. Populations should start to decline after two weeks and they should be gone after three to four weeks. Patience and calm are the best recommendations.
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 July 1, 2002 by Stephen J. Toth, Jr.
