The New International Encyclopædia/Mud-Wasp

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MUD-WASP, or Mud-Dauber. Any one of a group of wasps belonging to the old genus Pelopæus, now Sceliphron. They build nests of mud in sheltered places, choosing the cracks of a barn or fence or some sheltered place under the eaves of any wooden building, entering also disused rooms in houses, and sometimes even rooms that are in daily use. The nests consist of a varying number of mud cells placed side by side, usually in a single row, but sometimes in several rows. The cells before completion are packed with a food supply for the future young, and this consists almost invariably of spiders, as many spiders being placed in one cell as the cell will hold. A single egg is laid upon the last spider which has been placed in the cell, and the larva hatching from the egg eats rapidly, consuming the abdomens of the spiders first and subsequently the remainder of their bodies. All of the spiders which have been placed in the cell have been stung and paralyzed by the parent wasp, but many of them are not really dead when the larva reaches them. After the egg is laid and the nest is closed up, new cells are constructed by the same female. The mud or clay with which the nests are constructed is brought in little balls by the aid of the wasp's mandibles, and 20 or more visits are required to complete one cell; so that for the construction of a large nest of 50 cells about 1000 visits must be made by the insect. The larva reaches full growth in a short time, usually ten days or two weeks, and forms a cocoon within the mud cell, the winter being passed in the cocoon, although there may be two or more summer generations, in which case the summer pupal period is short. The group is a large one, and mudwasps are common not only in America and in Europe, but in India and Australia. Consult: Fabre, Insect life (London, 1901); Sharp, Cambridge Natural History, vol. vi. (London, 1901); Howard, The Insect Book (New York, 1902). See also the article Wasp and its bibliography.