mealybugThe mealy bug is the common name for one of the most destructive plant pests in the garden.  It belongs – like other scale insects to the Coccoidea super family and reproduces very fast, laying its eggs under a cotton like covering. They are laid in large numbers and so the mealy bug acquires resistance to pesticides fast.

The mealy bug is about 1 – 3 mm in size and has a powdery waxy covering, which protects it from pesticides.  They have well-developed legs and are therefore very mobile.  They live on the plant and at times on the roots.  If left untreated they are capable of killing the plant.

 SYMPTOMS

a. The plant looks as though it has patches of cotton wool on the leaves or stem.
b. Ants on the plant are a sure sign of some insect problem, not only mealy bug. They carry the mealy bug around the plant to the best feeding area. The ants feed on the honeydew.
c. The leaves are covered in a sticky liquid; this is the excreta of the mealy bug and is called honeydew.
d. The leaves look as though they have a black sooty covering.  This is Black Sooty Mould, which grows where the honeydew has fallen on the leaves.  If left untreated the Black Sooty Mould will kill the plant as it is unable to photosynthesise through the mould.

MANUAL CONTROL

It is important to deal with mealy bug as soon as it is noticed on a plant.

If the infestation is small, picking off the bug by hand or using a small paint brush works well.  The plant needs to be watched for several days to ensure all bugs are gone and no eggs have subsequently hatched.

Home made spray can be tried. Mix one cup of vegetable oil with four tablespoons of dishwashing liquid.  Bottle and label to ensure the contents are not accidentally used for something else. Spray the plant with a mixture of 1 litre of water to 2 mls of the mixture.

If the plant is badly infected, prune out the infection and destroy the waste material.  This must be done carefully to ensure all the bugs and their eggs are removed from the area.

CHEMICAL CONTROL

All sorts of chemicals are available.  If these are used it is advisable to change the brand from time to time due to the mealy bug becoming resistant. Spray preferably in the late evening or very early morning before bees and good insects are also killed.  When using spray read the instructions carefully and make sure non reaches your hands or eyes.  personal protection from chemical spray is very important.

 

Mealy bug damage to hibiscus

Mealy bug damage to hibiscus

 

Black Sooty Mould on leaves – ugly and damaging

Black Sooty Mould on leaves – ugly and damaging