What is Scale?
Scale insects are brown lumps found on the stems and leaves of your plants. They have hard protective shells and are about 2 – 4 inches long. The insects excrete honeydew sap for ants and wasps to feed on for protection against natural predators like ladybugs. This sap residue can lead to sooty mould that further damage your plants. Scale, if not controlled, will weaken your plants and turn leaves yellow and limp.
How to Identify Scale Insects?
Scale insects are small round or elliptical insects that vary in size but are typically 1 to 4 inches. There are two types of scale insects, armoured scale and soft scale.
Anomers scales have their own dry, protective covering, whilst soft scales produce waxy shells and honeydew. Honeydew is a sugary waste material that can attract other insects like ants and wasps. When this material is left unconsumed, it eventually rots, creating a black fungus called sooty mould. Sooty mould on leaves can be removed with warm water and a cotton cloth.
If the bugs on your houseplant are white and have a cotton-like webbing, those are mealybugs. Find our blog on mealybugs to help with your infestation.
What Does Scale Look Like?
Female and male scale insects vary significantly in appearance. Female scales resemble little bugs that, as their name suggests, look like small scales growing along with a plant or leaf. They have no legs and can't move locations once they've chosen to feed. Male scales are rare to encounter, and they resemble flying insects. They have a head, thorax, abdomen, a pair of antennae, and six legs; most species even have functional wings and tails. The male scale does not have a long life cycle, whilst females can live for 8 to 10 weeks, while males live for 2 to 3.
Lifecycle of Scale Insects
Scales insects go through one or two generations per year, making them slow breeding insects. Most species hatch from eggs whilst some a birthed live. Both males and females form legs and are referred to as 'crawlers'. They'll both shed their skin several times as they grow larger and look for feeding spots. Males will develop their body parts whilst females will find a place to feed and shed their legs, fixing them to one location for the rest of their lives. Male scales can't feed on plants and die several days after emerging.
How to Control Scale?
Once you know what scale looks likes, you can start inspecting your plants for them. Scale insects feed on trees, shrubs or even houseplants. They will settle on leaves and stems as those are the most significant sources of moisture.
The common signs of an infestation are:
Black sooty mould from honeydew.
Warped or stunted plant growth.
Some types of scale will produce cotton-like webbing; these are called mealybugs.
When starting treatment, ensure you wear gloves and protect your eyes. For houseplant treatment, you can use cotton buds dipped in rubbing alcohol and apply on top of each scale, or for more extensive treatments, mix alcohol and water in a spray bottle and cover the entire plant.
Washing and removing the scale is the only way to end the infestation. Using neem oil and possession soap will moisturise the leaf and prevent bugs from gripping and holding; this natural biological product is a great way to remove any hard-to-get pests. The residual effect of neem oil will also help prevent future pest problems.
What Damage Does Scale Cause?
Scale is one of those pests that usually goes unnoticed until it's too late. They can kill or stunt the growth of plants, cause black mould to form on leaves, or even attract from other pests like ants or wasps. Scale insects may be tiny, but they can cause trouble with seemly healthy plants. Thankfully, the damage caused by scale insects is not as quick or deadly as spider mites, for say, but it can still cripple a plant.
It's hard to remove scale from plants the first few times, but you'll be ready to fight any infestation once you know the tricks.
Remember: inspect your plants regularly and deal with problems before they escalate.