Scale insects

What are scale insects? Scale insects (Hemiptera: Sternorrhyncha: Coccoidea) are a group of small, plant feeding insects closely related to aphids and whiteflies. They are characterized by their unusual shapes, so much so that it is sometimes hard to recognize them as insects or even as animals! Adult females hardly ever move, lacking wings and often even legs. Instead of being able to run away, they have evolved many other ways to protect themselves against danger, including a variety of protective secretions. For instance, the armoured scales hide under a toughened shield, whilst mealybugs cover themselves with white grains or strands of wax (Figure 1). Many felt scales on the other hand recruit the plants they infest to help protect them, forming galls on the host plant. All told, there are almost 8000 species of scales across about 32 different families, of which the mealybugs and the armoured scales are the most numerous. Scale insects are found across the world, feeding on the leaves, roots and stems of a wide variety of host plants, and even under the bark of trees.