Adult Description: Positive identification of the pink hibiscus mealybug (Maconellicoccus hirsutus) requires a professional entomologist. Heavy cotton like, white, waxy buildup on the terminals, stems, and branches of infested host plants may indicate a severe mealybug infestation. The adult female is about 3 mm long and wingless with white, flocculent wax covering the dorsal surface. It has two short, inconspicuous caudal filaments and no lateral wax filaments. The female's body and body fluid are both reddish. Smaller than the female mealybugs, adult males are reddish brown and have one pair of wings and two long wax caudal filaments. The males have nonfunctional mouthparts. Males do not feed and live for only a few days. Unmated females produce a sex pheromone (an attractant scent) that lures pink hibiscus mealybug males for mating.
Larva Description: Eggs are pink, minute, and contained in an egg sack of white wax. Newly hatched nymphs are called crawlers, and are very mobile. They may disperse over the host, especially toward tender growing parts, or be carried away by wind, man, or animals. The nymphal stages appear much like the female in form, but the female nymphs have three instars, while male nymphs have four instars. The last instar of the male is an inactive stage with wing buds within a cocoon of mealy wax. The nymphal stages may last for as long as 30 days. The hibiscus mealybug can complete its entire life cycle in 23 to 30 days. Under optimum laboratory conditions, there can be as many as 15 generations a year.
Host Plant: Infects its namesake, Hibiscus, but also citrus, coffee, sugar cane, plums, guava, mango, okra, sorrel, teak, mora, pigeon pea, peanut, grapevine, maize, asparagus, chrysanthemum, beans, cotton, soybean, cocoa, and many other plants.
Ecological Threat: The pink hibiscus mealybug sucks juices from its host plant and injects a toxic saliva as it feeds. This process leads to the malformation of leaves and fruit, as well as stunted leaves and terminal growth, which is commonly called "bunchy top". Feeding by this mealybug's can also lead directly to the death of its host plant.
Biology: Natural spread is slow for this group because they are not strong fliers. Instead their movement is facilitated by human activities and on ornamental plants. Infested fruits may be entirely covered with the white waxy coating of the mealybug. Sooty mold may develop on honeydew secretions of the mealybug. The movement of infested plants and plant material is not advisable as this may spread the pink hibiscus mealybug to new areas.
History: Since it arrived in Grenada in 1994, the pink hibiscus mealybug has spread to Guyana in South America and at least 14 other Caribbean islands. It has been found in Hawaii, Florida, and Southern California. If proper precautions are not taken, the pest will surely spread throughout the U.S. especially along the semi-tropical southeastern states.
U.S. Habitat: Lives in most tropical areas throughout the world. Established in Asia, Africa, India, and Australia.
Native Origin: Most tropical areas of the world including Africa, India, Australia, and Asia
U.S. Present: The pink hibiscus mealybug has made it into Southern California and into Florida. There is a concern that the Pink Hibiscus Mealybug will spread all across the southern U.S., especially the southeastern states due to their semi-tropical habitat preference.
While not currently in Texas, there is a potential that the pink hibiscus mealybug will spread throughout the state rapidly. Be sure to observe imported plants from the nursery for the signs of infestation.
The pink hibiscus mealybug resembles other scale-type and aphid-like insects that are found on plants. Very difficult to properly identify, so it is best to look for the signs of an infection. A professional entomologist is needed for an accurate identification.
In general, the use of pesticides is ineffective against M. hirsutus, partly because of its habit of hiding in crevices and because pesticides cannot penetrate the heavy layers of wax that shield the body. The egg stage in particular, is protected by a white, waxy ovi-sac, which most pesticides cannot penetrate.
The pruning and burning of infested material has been used in an attempt to control M. hirsutus in places such as Trinidad following the discovery of an infestation. However, these efforts are ineffective in slowing it's spread.
Encyrtid wasps (Hymenoptera: Encyrtidae) have been used frequently as highly specific parisitoids of M. hirsutus. These parasitoid wasps lay eggs within the adult individuals of M. hirsutus. Coccinellid beetles (Coleoptera: Coccinellidae) such as C. montrouzieri and Scymnus coccivora are also used as generalist predators of mealybugs such as M. hirsutus and often released simultaneously with the aforementioned wasps.
Ghose SK. 1972. Biology of the mealybug, Maconellicoccus hirsutus. Indian Agriculture 16:323-332.
Rao VS, Srinivasan S. 1987. Maconellicoccus hirsutus, a new pest of groundnut in Andhra Pradesh. Entomology. 12: 115.
USDA-APHIS. 1997. Field releases of nonindigenous species of Anagyrus and Gyranusoidea (Hymenoptera: Encyrtidae) for biological control of pink hibiscus mealybug, Maconellicoccus hirsutus (Homoptera: Pseudococcidae). Environmental Assessment. 8 pp.
Williams DJ. 1996. A brief account of the hibiscus mealybug Maconellicoccus hirsutus (Hemiptera: Pseudococcidae), a pest of agriculture and horticulture, with descriptions of two related species from southern Asia. Bulletin of Entomological Research. 86: 617-628.