Page:Popular Science Monthly Volume 61.djvu/347

Rh preference seems to be for the sloping under side of old roofs, eaves and the protected casements of windows. Indeed, so strong has been the attachment to certain sites, that I have several times seen the wasps suspending one comb from another in the style of architecture characteristic of the hornet. In New England P. pallipes builds in the. open on wild rose bushes and other low shrubs, in protected recesses of stone walls, while a tin can, a water pipe perforated by rust and a sheep's skull are other nesting places which have come to my notice. At Willow Grove, Pa., great numbers have made use of the space enclosed by the sheet-iron water-table of a new car barn, thus securing a maximum of warmth and immunity from the zealous wasp hunter. In Texas, I am told, certain species build on the cacti, while others prefer stone ledges; and doubtless further observation will disclose many other interesting variations in the nesting habits.

The nest, as is well known, consists of a single layer of hexagonal paper cells. It is modeled from a soft gray pulp which is a mixture of fibers of weather-worn wood and a secretion from the wasp's mouth. The little ball of semi-fluid pulp is applied roughly by means of the fore legs, all along the edge of the cell to be extended, making an irregular addition about four times as thick as the cell wall. The wasp then walks back and forth for two or three minutes continually touching the material with her antennae, and with her mandibles pats and smooths it into shape. This operation extends the wall each time from one eighth to one fourth of an inch, depending of course on the size of the ball of material at the beginning. In addition to this, the wasp applies a glutinous secretion which renders the paper tough and waterproof, the nests built in the open being more thickly coated than those sheltered from the rain and dew.

The geometrical sense of the bees and wasps has long been a matter of controversy. In Polistes, so far as I have observed, the first cells always approach a circle in cross-section, and the six-sided form is the result of the flexibility and the consequent compressing of the walls. Once pressed into shape, the material added may take the same form, and the artificer appears to possess a superior mathematical sense; but that the cells are not intentionally fashioned thus may be seen by examining those first formed, or those comprising the margin of the nest at any later stage of construction. These are always circular in outline.

The larvae, which develop in a few days from the eggs, are fed from this time until the beginning of the pupal stage both with nectar and proteid matter. The nectar is obtained from flowers, is stored for a