Mealybugs (and scale insects in general) can be pests of the garden, if their numbers grow to uncontrollable levels, since they feed off plant sap like mosquitoes do to humans. Mealybugs are actually very closely related to scale insects, but lack the waxy outer shell, and are able to move about at will (albeit very slowly), whereas scale insects are stationary once they are feeding.
Mealybugs are extremely common and found all over the world and in nearly every garden as well (except for perhaps the most sterile of gardens). If your garden does not have mealybugs, you ought to be worried, as they are one indicator of a normal and functioning garden ecosystem. But their incessant sucking of plant juices causes weakening of the plant, leading to poor growth, leaf drop, or even death. Therefore, mealybugs can become a garden pest if allowed to multiply. The honeydew that they secrete also gives rise to a type of black mold that may breed unhealthy vectors and pathogens.
It is the female mealybugs that are the ones you normally see on plants; the males live only a short while to fertilize the females, have wings, and look more like insects, while the females have a grub-like nymph look. They secrete a powdery wax covering to protect themselves, and in some species, lay their eggs in this wax layer.
One common home remedy for minor mealybug infestations that occur indoors is to daub them with cotton swabs dipped in rubbing alcohol. For outdoors, using a jet stream of water to hose down your plants every 2-4 weeks also works in controlling mealybugs.
Mealybugs have developed a symbiotic relationship with some ant species. The ants will tend to the mealybugs, shelter them, and protect them from predators; in return, the mealybugs secrete honeydew for the ants. This is rather like humans and their herds of livestock.
Nonetheless, ladybugs are an effective natural mealybug predator, and should be encouraged to thrive in your garden as much as possible. Other natural predators of mealybugs are lacewings. Controlling the ant population also helps in dealing with mealybugs.
Be careful about using insecticide against mealybugs as it can also kill the mealybug’s natural enemies. A few pesticides that have been tried against mealy bugs are malathion and diazinon. Horticultural oils (#affiliatelink) are also effective against mealybugs.
