The true social wasps, which are arranged in one large family, the Vespidæ, form communities whose architectural labors will not suffer on comparison even with those of the inhabitants of the beehive. In fact, for daintiness and delicacy the nests of many of the Vespidæ constitute the most beautiful examples of insect architecture.
Not the least extraordinary of the wasps are the Icarias, a genus that extends through most of the warmer regions of the Fig. 2.—Nest of Icaria variegata. world, specimens having been taken in Africa, India, China, and Australia, and in many parts of the Asiatic Archipelago. Like the Polistes, their nests are attached to leaves, stalks, or branches by a single foot-stalk, composed of the same papery material as the cells. Though slender, it is hard, tough, and solid, and the strength with which it is fastened to the tree or plant is surprising, enabling it to uphold considerable weight. At the end of the petiole usually a single cell, its mouth directed downward, is fixed; the rest of the nest consists of a double series of lateral cells until the group is complete. Those nearest to the footstalk are the largest and most perfect, since they are finished first; toward the other extremity the cells gradually diminish in size, and at that point they are only just begun. As a whole they are well-defined hexagons; their color is often a rather dark yellowish brown, preventing them from being conspicuous in spite of their curious projection. The cell masses are small, so that the societies must be restricted. Possibly each group is the work of a single female, who confines herself to raising her own progeny which escape as soon as they are hatched. The nests are frequently numerous in the same spot, and each society may set up a number of separate homes in the vicinity of one another. Per-