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Ornamentals and Turf |
It seems a little early for yellowjackets, but populations of almost every other pest have been early this year. Summer is the time when unsuspecting lawn-mowing homeowners suddenly come across a yellowjacket nest in their yards. (This assumes we will ever have enough rain for the grass to grow again.) These nests have actually been growing since spring and have only recently reached a critical mass where they react defensively.
Yellowjackets are house fly-sized wasps with distinct yellow and black-colored markings and a few hairs. Their nests are found in the ground 99 percent of the time. They are not good diggers. Therefore, they choose cavities which were formerly rodent borrows, buried rotted logs, bases of nursery grown shrubbery, or gaps under masonry to start their new nests. Underground they construct a paper nest similar to a common hornet; however, it will be tan in color and much smaller in size. Occasionally, yellowjackets will nest in attics or walls voids of houses or storage buildings.
Yellowjackets may also be late season pests around picnics, trash cans, ripened fruit and humming bird feeders as they scavenge for food or moisture. Later this summer we might expect more interaction of humans and yellowjackets as both frequent pools and picnics. To help manage this interaction, keep food and trash covered and promptly clean up food spills. Yellowjackets are especially adept at flying into open cans of soda. The only way to control this situation is to locate the nest, which is rarely possible, and destroy it.
If the location of the nest is known, do not pour gasoline down the hole to destroy it. Use an aerosol hornet and wasp killer sprayed directly into the hole at night. A second treatment is sometimes necessary.
Do not forget that yellowjackets can be helpful too, because they prey on other insects. One additional note is that I have not seen data to make me believe that yellowjacket traps catch adults or lower populations in this part of the country. You can find information about yellowjackets on the Internet at: http://www.ces.ncsu.edu/depts/ent/notes/Urban/horn-yj.htm. Methods of reducing the probability of stings can be located at: http://www.ces.ncsu.edu/depts/ent/notes/Beekeeping/bee15.html.
The azalea stem borer is a small, slender longhorned beetle that emerges from damaged azaleas and rhododendrons in late spring after the new vegetative growth has matured. These beetles fly to the new growth and chew a series of holes around the stem and then another series of holes one-forth to one-half inch away. Between these rows of holes the beetles insert an egg into the bark. Within a few weeks this egg matures and a slender, white grub hatches and begins to feed within the stem. Infested stems often wilt. As the grub bores downward, the stem dies and wilts above the area girdled by the beetle. The grub continues to bore downward and eventually reaches the base of the plant where sawdust and other waste products are pushed out of holes onto the ground.
The grub usually overwinters in a cell excavated inside the plant close to the ground. The following spring the grub matures and molts into a pupal stage. A few weeks later, a new generation of beetles emerges from infested plants to continue the life cycle. Infested branches often die or they are so weakened that these branches break off easily. Infested stems can be pruned as soon as wilting is noticed in early summer (the stems have to be pruned below the grub, otherwise the grub continues boring down toward the roots). These stems should be burned or otherwise destroyed in the slim chance the grubs might survive to produce more beetles next year.
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 15, 2002 by Stephen J. Toth, Jr.
