A fringe of waxy filaments may be present on the margin of the body. Adult females are 1/20–1/5 inch (1.0–5.0 mm) long and are usually covered with a white, powdery, waxy material. Mealybugs are soft-bodied, segmented, oval-shaped insects. Mealybugs feed on a wide range of plant hosts including coleus, croton, dracaena, English ivy (Hedera helix), fuchsia, gardenia, hibiscus, mandevilla, stephanotis, palms, orchids, and cacti and succulents. The presence of black sooty mold fungi inhibits the ability of plants to manufacture food via photosynthesis, and detracts from the plants' aesthetic appearance. While feeding, mealybugs may inject toxic saliva into plant tissue, and excrete copious amounts of honeydew that serves as an excellent growing medium for black sooty mold fungi. Both nymphs (referred to as crawlers) and adults feed on plants and cause stunting, leaf yellowing, and distortion of plant parts. Mealybugs use their piercing-sucking mouthparts to withdraw plant fluids. Mealybugs usually enter a greenhouse on infested plant material. and which may also be present in greenhouses, include the pink hibiscus mealybug (Maconellicoccus hirsutus), madeira mealybug (Phenacoccus madeirensis), and the Mexican mealybug (Phenacoccus gossypii). Other mealybugs that have been introduced into the U.S. Be sure to disinfest containers before reusing them. If a greenhouse is infested with root mealybugs, all infested plants and debris should be immediately discarded and replaced. Root mealybugs may also infest adjacent plants by crawling through drainage holes of containers. Once introduced into a greenhouse, root mealybugs may spread to other plants in water leaving drainage holes of containers, in growing medium or plant debris, or on equipment. Damage is usually noticeable when high populations are present. Root mealybug feeding causes stunting and leaf yellowing. Nymphs are covered by a white waxy material, and are located in the crevices of growing medium or in excavated chambers on the outer edge of the root ball. Root mealybugs do not possess the marginal filaments that are typical of other mealybugs. These mealybugs, which are not as active as mealybugs that feed above-ground, are typically covered with a fine, powdery, wax-like material. They appear as masses of wax and may occasionally be detected on the roots of wilting plants. Generally these insects are slow-moving and sac-like in shape. Obscure mealybug also has waxy filaments but they are much shorter than those of longtailed mealybug. Longtailed mealybug can be a major problem on plants grown in conservatories (e.g., cycads, orchids and ferns). This species produces living young instead of eggs and can be identified by their long waxy filaments that protrude from the end of the abdomen. Longtailed mealybug (Pseudococcus longispinus) This species may lay up to 500 eggs in irregular cottony masses. The following are the most important greenhouse species:Ĭitrus mealybug (Planococcus citri) PhotoĬitrus mealybug lacks any waxy filaments on the body and has a gray stripe that extends the length of the body. They are typically a problem in interiorscapes and retail greenhouses in Massachusetts and on long-term crops such as cut flowers, orchids, and foliage plants. Mealybugs are often introduced into greenhouses on infested plants.
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