Mealybugs are
sexually dimorphic: females appear as nymphs, exhibiting reduced morphology, and lack wings, although unlike many female scale insects, they often retain legs and can move. Males are smaller, gnat-like and have wings. Since mealybugs, as well as all other
Hemiptera, are
hemimetabolous insects, they do not undergo complete metamorphosis in the true sense of the word. However, male mealybugs exhibit a radical change during their life cycle, changing from wingless, ovoid nymphs to
wasp-like flying adults. Mealybug females feed on plant sap, normally in roots or other crevices, and in a few cases the bottoms of stored fruit. They attach themselves to the plant and secrete a powdery
wax layer (hence the name "mealy" bug) used for protection while they suck the plant juices. The males are short-lived, as they do not feed at all as adults and only live to fertilize the females. Male citrus mealy bugs fly to the females and resemble fluffy
gnats. Some
species of mealybug lay their
eggs in the same waxy layer used for protection in quantities of 50–100; other species are born directly from the female. The most serious pests are mealybugs that feed on
citrus. Other species damage
sugarcane,
grapes,
pineapple (Jahn et al. 2003),
coffee trees,
cassava,
ferns,
cacti,
gardenias,
papaya,
banana,
mulberry,
sunflower and
orchids. Mealybugs only tend to be serious pests in the presence of ants because the ants protect them from predators and parasites. Mealybugs are also a vector of viruses in grapevines, spreading grapevine leafroll and grapevine red blotch viruses. Mealybugs also infest some species of
carnivorous plant such as
Sarracenia (pitcher plants). In such cases it is difficult to eradicate them without repeated applications of
insecticide such as
diazinon. Small infestations may not inflict significant damage. In larger amounts though, they can induce leaf drop. In recent years, some of the mealybug species have become invasive pests in localities posing a great problem to the new
agro-ecosystems. In
India,
Withania somnifera plant have been reported as a new reservoir host for an invasive mealybug species
Phenacoccus solenopsis. Some mealybugs of the
Hypogeococcus are used as
biological pest controls of invasive cacti in
South Africa, including
Harrisia balansae,
H. martinii, and
Opuntia cespitosa.
Fossil specimens of genus
Acropyga ants have been recovered from the
Burdigalian stage
Dominican amber deposits and several individuals are preserved carrying the extinct mealybug genus
Electromyrmococcus. These fossils represent the oldest record of the
symbiosis between mealybugs and
Acropyga species ants. File:Maconellicoccus hirsutus - hibiscus mealybug - adult male.jpg|Male
hibiscus mealybug,
Maconellicoccus hirsutus File:Formica fusca and mealy bugs.jpg|
Formica fusca ants tending a herd of mealybugs File:Ladybug(india).jpg|A
ladybird preying on mealybugs File:Mealybugs feeding on hibiscus plant.jpg|alt=Mealybugs on Hibiscus plant.|Mealybugs on hibiscus plant File:Phenacoccus aceris.jpg|
Phenacoccus aceris File:Acropyga glaesaria SMFBE457B2 01.jpg|
Acropyga glaesaria ant carrying an
Electromyrmococcus abductus mealybug ==Control methods==