Scale insects

Ecology

Scale insects in the genus Cryptostigma live inside the nests of neotropical ant species. Many tropical plants need ants to survive which in turn cultivate scale insects thus forming a tripartite symbiosis. Some ants and scale insects have a mutualistic relationship; the ants feed on the honeydew and in return protect the scales. On a tulip tree, ants have been observed building a papery tent over the scales. In other instances, scale insects are carried inside the ant's nest; the ant Acropyga exsanguis takes this to an extreme by transporting a fertilised female mealybug with it on its nuptial flight, so that the nest it founds can be provisioned. This provides a means for the mealybug to be dispersed widely. Species of Hippeococcus have long clinging legs with claws to grip the Dolichoderus ants which tend them; they allow themselves to be carried into the ant colony. Here the mealybugs are safe from predation and environmental hazards, while the ants have a source of nourishment. Another species of ant maintains a herd of scale insects inside the hollow stems of a Barteria tree; the scale insects feed on the sap and the ants, while benefiting from the honeydew, drive away other herbivorous insects from the tree as well as preventing vines from smothering it.