Related Topic: Honey Bee Parasites, Pests and Predators - New slide set, viewable on Web

Larvae of the greater wax moth, Galleria mellonella, cause considerable damage to combs left unattended by bees. Combs in weak or dead colonies and in storage areas are subject to attack. Wax moths pose a continuous threat except when temperatures drop below 40 degrees F. Strong colonies keep these grayish white larvae under control.

Adult female moths fly at night and deposit masses of eggs on unprotected honeycombs and in the cracks between hive bodies. After a few days these larvae hatch, crawl onto the comb, and begin their feeding activity. They damage or destroy the combs by boring through the cells as they feed on cocoons, cast skins, and pollen. As they chew through the wax, they spin silken galleries for protection. (See Figure 39.) Combs are often reduced to a mass of webs and debris. (See Figure 40.) Wax moth larvae seldom attack new combs and foundation.

Larval developmental time depends on temperature. The larval stage may last from twenty-eight days to five months, depending on nutrition and environmental conditions. During this period, larvae may vary from 1/25 inch to 1 inch in length.

When fully grown, the larva spins a rough silken cocoon, which is usually attached to the frame or inside of the hive. Frequently the larva cements the cocoon inside a cavity chewed in the wood. Chewed frames are weakened and easily broken. Within the cocoon, the larva changes to the pupa and overwinters in the pupal stage. Under warm conditions, adults may emerge at almost any time of year.

At the present time, two approaches can be used to protect combs: paradichlorobenzene and cold temperatures. When placing combs in storage, be sure to kill any existing stages of wax moth and guard against later infestations. Freezing weather kills all stages of wax moth, so some

Figure 39. Comb damaged by wax moth attack. Note webbing and tunneling by feeding larvae.

Figure 40. A comb completely destroyed by wax moth.

beekeepers keep supers on the bees until after a killing frost. Supers are best stored outside in the cold or in a dry unheated building. Many beekeepers store a portion of their supers in stacks in each bee yard so that they are ready for use in the spring.

Paradichlorobenzene. If supers must be stored in a warm room or basement, they may be protected by placing paradichlorobenzene (PDB) crystals on a small piece of paper on every fifth super in the stack, which should then be covered. The treatment must be continued at regular intervals all winter. PDB kills adult and immature wax moths, but not eggs. The continuous presence of crystals within the stack not only repels moths and prohibits egg laying, but also kills any young larvae that hatch after the combs are placed in storage. Untreated combs should be inspected regularly for signs of infestation, especially if temperatures rise above 60 degrees F and permit wax moth activity. Supers should be aired before using them in the spring. CAUTION: Moth balls and crystals (naphthalene) should not be used to control wax moth.

The larvae of the wax moth do considerable damage to comb honey. The eggs are probably laid on the comb or section boxes before the comb honey supers are removed from the hives, but the damage does not become evident until sometime after the honey has been placed in storage.

Cold Temperatures. PDB can be used to protect all combs in storage except those containing honey intended for human consumption. The odor of PDB is readily absorbed by honey, and, though the bees do not object to this odor, such honey is unfit for human consumption. The only approved method for preventing wax moth damage to comb honey is freezing. The USDA recommends a temperature of 0 degrees F for twenty-four hours to kill wax moth. Small amounts of comb honey can be stored in the freezer. This not only prevents wax moth damage but also retards crystallization.

Related Topic: Honey Bee Parasites, Pests and Predators - New slide set, viewable on Web