A Matter of Scale

Small creatures, big results

Detail of the coronation mantle of Roger II of Sicily. Made of silk dyed with kermes derived from scale insects and embroidered with gold thread and pearls. Made in the Royal Workshop, Palermo, Sicily, 1133–34, and now in the collection of the Kaiserliche Schatzkammer, Vienna, Austria. Source. © Brad Hostetler. CC BY 2.0

Having survived stick insects, caterpillars, and giant grasshoppers, my plant collection is facing a new adversary — scale insects. At least three species have latched onto the leaves and stems, coating them in white fluff, brown oystershells or, the most spectacular of the lot, minuscule pink buttons. In several ways, it is a matter of scale.

Scale insects are bugs. Real bugs, that is — true bugs. True bugs belong to order Hemiptera, a huge group of insects that includes aphids, cicadas, leafhoppers and the spectacular lanternflies. They feed by sucking sap from plants. To do this, their mouthparts are adapted for piercing plant tissue. In some species, those mouthparts are turned to piercing animal skin. Instead of sap they feed on blood. Bedbugs (Cimex) are blood-feeders. So are kissing bugs (Triatoma and others), who take your blood and might leave you with a trypanosome infection in exchange.

Scale insects only feed on sap. Adult females are sedentary, while the young ones and adult males (where they occur) go wandering. Because sitting still is a perilous prospect, female scale insects cover themselves with protective structure: white fluff, brown oystershells or minuscule pink buttons. There are as many coverings as there are species.