Mealybug
Overview:
Mealybugs affect mainly indoor and greenhouse plants e.g cacti, and some citrus fruits.
They are seen as soft-bodied, greyish-white, wingless insects up to 5mm (¼in) long, often with white, waxy filaments trailing from their bodies.
In certain species, reproduction under greenhouse conditions is year-round.
All individuals are female, and reproduce without the need for males.
This means the nymphs or young are achieved without fertilization, therefore the escape of a single individual may allow the infestation to continue.
Some mealybug species can produce 100-300 eggs.
The egg is sac covered with waxy secretions.
Development from egg to adult takes about three weeks.
A by-product of mealybug feeding is sticky honeydew which coats infested foliage.
Mealybugs, like aphids, are active throughout most of their life.
Infestations are frequently visible on indoor pot plants, succulents, cacti and others grown in relatively dry compost.
The infestations can occur within the vegetative shoot apex, making them extremely difficult to detect and control.
Heavy infestations can cause plants to suffer from a lack of vigour.
Control:
Some insecticides may help to control infestations, but the most effective method, is to use a natural predator such as crytptolaemus montrouzieri.
In warmer months introducing ladybirds is a good biological control.
Alternatively, using a natural fatty acid spray at two weeks may help.
However vigilance is often the best form of attack.
Check susceptible plants regularly and deal with the first signs of any infestation immediately.
This can be done by either removing the individual pests by hand or,in the case of some types of plants, cut off infested shoots and stems, and destroy them.
Remove dead leaves and plant debris from the greenhouse in the event that these may harbour adults or eggs.
If a much loved plant becomes infected, take cuttings from it, and discard the rest, including the potting compost.