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Gall-Like Scale Insect

Kermes (?)

Kermes scale insect on Quercus photo © by Mike Plagens

Pinal Peak, Gila Co., Arizona. 29 July 2011. These sessile bugs are attached to the woody twigs of Arizona White Oak. The ants are gathering sugary honeydew from the surface of the bugs' casings.

Kermesidae -- a Family of Scale Insects

An understanding of what insects are from a basic biology course does not prepare one to identify these blobs as insects. For one thing they are immobile without visible legs. Next they are encased in a waxy, spongy material that obscures all body parts including the head and mouthparts. Scales have piercing-sucking mouth parts and once attached to an acceptable spot on a plant they settle down as their legs and eyes atrophy. The cover provides some protection from the elements and also some predators. Plant sap is their sole food, but it has too much sugar relative to other required nutrients and so it is excreted as a waste product. Ants and wasps are keen to exploit this and in the photo at left several Wood Ants can be seen in close attendance. When the scales reach maturity and after the eggs have hatched the old dead casings remain attached to the tree twig. This species is not common and seems to specialize on Arizona White Oak.

Kermes scale insect on Quercus photo © by Mike Plagens

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Copyright Michael J. Plagens, page created 25 Dec. 2016.