Scale insects vary dramatically in appearance; from very small organisms (1–2 mm) that grow beneath wax covers (some shaped like oyster shells, others like mussel shells), to shiny pearl-like objects (about 5 mm), to creatures covered with mealy wax. Adult female scales are almost always immobile (aside from mealybugs) and permanently attached to the plant they have parasitized. They secrete a waxy coating for defense; this coating causes them to resemble reptilian scales or fish scales, hence their common name.1
Scale only move during the first and second stages of their life cycle. This is when they are relatively small, searching out a suitable site to grow big and fat and start giving birth to live young. 99.9999% are females, and they go right into action as soon as a suitable feeding site is located.
Pests seem to know when the days start to get longer, so any plant material that is container grown, and that spends a good portion of it’s life outside during the warmer weather is at risk of having a pest outbreak. Eggs that were layed, hatch, and/or hibernating females start waking up with the turn of the year. This is nature’s way of getting food ready for predators which are still sleeping through the winters chill. Their life cycles are tied to the temperature; the warmer (24-25’C) it is, the shorter the time for each life cycle of egg or live birth, to adult, to reproduction. Keep a watchful eye out for the tell tale signs of trouble, such as honey dew on leaf surface, which is actually the by-product of insect feeding. If you are able keep your plants cool, it will slow the cycle down.
When placing your plants outside in the spring keep a watch for ants. Harmless really to the plants, but great opportunist farmers. If your plants do not have pests (ants are attracted by, and eat the sugary ‘Honey dew’), then they will quite literally stock your plants with what they need, which can be any type of sap sucking insect. They do mainly use Aphids, but do use Scale, as they are easier to herd (Scale do not produce winged adults which can fly away!).
For control, squishing the adults and young, and wiping the plant leaves gently with a wet cloth/tissue, which has a very weak soap solution (1 in 200) works well. Be sure to focus around and along the leaf veins, and both sides of leaf.
Here at ToC, we use two types of Beneficial Insect for Scale control. Both are small beetles. Their use is dependent on how bad the problem is. We apply Delphastus catalinae every month, as this will feed on any insects it can find. The second, Lindorus lophanthae, which is a scale first beneficial. will be applied if we think the Delpastus is not making progress. When outside during the warm months, we add Ladybugs (Canadian), as well as Praying Mantis. We have been doing this for two years in the garden, and as the photo’s show from last year, we now have a small resident population of both.
All Beneficials are obtained from NIC, Natural Insect Control.*
*Please note: Though we recommend various companies on our website, we have no affiliation or commercial link with any of them.