Mealybugs get their name from the white, powdery wax material which is seen covering the bodies of the adult females and nymphs. Females and nymphs can also be commonly seen with white waxy filaments extending from the margins of their body.
Mealybugs are also closely related to Scale Insects, and just like their cousins they are also sap suckers. It is this characteristic that can result in leaf damage on their host plants. This can be quite severe and include the wilting and distortion of new leaves. Mealybugs excrete a large amount of a sugaring substance called; honeydew, which often encourages the growth of Sooty Mould. This can also damage plants further.
What are Mealy Bugs?
Mealybugs (Pseudoccidae) are sap sucking insects. They are related to Scale Insects. There are several hundred species of Mealybug, many of which are native to their environment. But in many countries around the world, there are also many that are introduced to the location. Most commonly, the pest species encountered in gardens and on indoor plants are introduced.
Common pest species include:
- Citrus Mealybug (Planococcus citri),
- Citrophilous Mealybug (Pseudococcus calciolariae),
- Hibiscus Mealybug (Maconellicoccus hirsutus),
- Longtailed Mealybug (Pseudococcus longispinus) and
- Tuber Mealybug (Pseudococcus viburni).
In Australia, Citrophilous Mealybug is native, and the others are introduced.
Mealybug Description
Female Mealybugs are less than 5 mm in length and usually oval in shape. They secrete a powdery waxy material which covers their body. Some species also have filaments of wax extending around their bodies. Some species may also have very long filaments extending from the rear.
Adult males are rarely seen. They don’t feed and are only about 1mm long - very tiny compared with the females. They also have wings.
You will often see Mealybugs closely associated with a sticky mass of waxy threads - these are their eggs and while often white in colour, may also be pale yellow or orange, depending on the species.
Nymphs (crawlers) start off a yellow-brown in colour and do not have a waxy covering. Their waxy covering is developed at the second nymph stage.
Mealybug Life Cycle
Most adult females lay 300 to 600 eggs in a waxy egg sac over a period of 1 to 2 weeks, although some species lay live young.
Nymphs hatch from these eggs. Females will pass through three nymph stages before adulthood. Male Mealybugs have four nymph stages and only feed in their first and second stages before passing through two non-feeding stages. Adult males only live for a few days during which their role is to find females and mate with them.
The full life cycle typically takes from 6 to 12 weeks. This relatively short life cycle means that there can be several generations in a year resulting in the potential for them to become a problem if not dealt with early.
What Plants are affected by Mealybugs
- Fruits – especially citrus, Figs and Grapes.
- Many ornamental plants including Cactus, Fuchsia, Gardenia, Hibiscus, Jasmine and Oleander.
- Many houseplants including Coleus, Ferns, Ficus, Orchids, Palms and Philodendron.
- Greenhouse plants - Mealybugs love the warm, humid environment typically found in greenhouses and indoors.
What are the Symptoms of Mealybugs
- Wilting and distortion of new leaves.
- Leaf and bud drop.
- Sooty Mould on the affected plants - mealybugs exude excess plant fluids as honeydew, which promotes the growth of Sooty Mould.
How to Prevent Mealybugs Appearing
Monitor
- Montor the condition of the leaves of all your plants. Look out for Sooty Mould developing. The presence of Sooty Mould is an excellent indicator of sap sucking insect activity.
- Scan the leaves of your plants. Mealybubs like the points where the leaves join the branch - easier access to the ‘sappy’parts of the plant. You will often notice them as a white powdery and waxy material.
Prevent
- Ensure that you check all new plants and cuttings for Mealybugs (and other pests) before bringing them into your garden or house.
- Prune dense foliage to minimise sheltered and high humidity feeding areas.
- Ants, protect Mealybugs from predators and parasites. In return, the ants get a feed of honeydew. Monitor for ants clustering in numbers on parts of plants, and if necessary prevent the ants from climbing the plant by using a horticultural glue.
- Prune sections of plants that are heavily infested. Dispose of these pruning in a way that does not promote reinfestation.
Natural Enemies
- Several species of parasitic wasps.
- Lacewings and Ladybird species.
How to Get Rid of Mealybugs
Treating Mealybug Infestations
If you only have a few, dab methylated spirits directly onto the bugs with a cotton bud.
If you have an infestation, thoroughly spray the plant all over with neem oil, and repeat in 7 days.
If they continue ot persist, you may need to prune the affected section and dispose of these in a way that does not promote reinfestation.
