These pests of summer proceed from the animalcules commonly termed the " wiggle tail." If a bowl of water is placed in the summer's sun for a few days, a number of " wiggle tails " will be visible, and they will continue in size till they reach three-sixteenths of an inch in length, remaining longer at the surface as they approach maturity, as if seeming to live on influences derived from the two elements of air and water; finally they will assume a chrysalis form, and by an increased specific gravity sink to the bottom of the bowl. A few hours only will elapse when a short blank furze or hair will grow out on every side of each, till it assumes the form of a minute caterpillar. Its specific gravity being thus counteracted, it will readily float to the surface, and be wafted to the side of the bowl by the slightest breath of air. In a short time a fly will be hatched and escape, leaving its tiny house upon the surface of the water. Any one who has had a cistern in the yard has doubtless observed the same effect, every summer, although he may be ignorant of the beautiful and simple process of development. If a pitcher of cistern or other water containing these animalcules is placed in a close room over night, from which all musquitos have been previously excluded, enough musquitos will breed from it during the night to give any satisfactory amount of trouble. In fact, standing by a shallow, half stagnant pool on a midsummer's day, the full development of any number of " wiggle tails " to the musquito state can be witnessed, and the origin of these disturbers of night's slumbers thus fully ascertained.