Some of the intruding insects that come from oak galls are not
harmless. They are the ones called parasites. They live in the
houses not for the sake of the protection or the food furnished
by the house, but in order to eat the actual dwellers in the
house. Often and often not a single real gall-insect comes out
in the spring from many of the little houses, but only a little
swarm, or sometimes just two or three, or even one, of these
insect-devouring parasites that has eaten up the rightful owners
of the house.--VERNON L. KELLOGG, “Insect Stories.”
(2300)