Notes on the Locusta septentrionalis americanae decem septima / by Nathaniel Potter.

  • Potter, Nathaniel, 1770-1843.
Date:
1839
Catalogue details

Licence: Public Domain Mark

Credit: Notes on the Locusta septentrionalis americanae decem septima / by Nathaniel Potter. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    growth, and that the grub or pupa form is not assumed till a short time before they are found at the surface, of the earth. While the insect is under ground, gradually acquiring its growth, it performs the functions of digestion and excrementition, we find it furnished with a strait intestinal tube, the upper part of which is expanded into a wider receptacle, and seems to answer for a stomach. When the pupa leaves the ground and the body is almost matured, these organs seem to be almost obliterated, as we find only a wasted membrane that can perform no function, a mere remnant of former vitality. As little or no growth is required after the pupa state, there is no necessity for a stomach, and during the fleeting existence of the insect in open air, no excrementitious matter can be found. The cavity occupied by the digestive organs is now filled by the seminal fluid in the male and the eggs in the female. The time between the discovery of the pupa, and its final exit from the earth, is spent in maturing its skin, and acquiring strength to fit it for more active operations, to fulfil its destination. During the warmer hours of the day, it is seen peeping from its cell, seeming to enjoy the warm, fresh air. At twilight, or if the temperature fall during the day, they retire to their chambers. In this imperfect state, their progress is slow, and they are unfit to inhabit the open air for eight or ten days. They then cast off their slough, which finishes the short-lived chrysalis state, and become perfect locusts in twenty four hours, and sometime sooner—their progress depending, in some degree, on the temperature of the at- mosphere. If we descend to the bottom of their chambers, we find them (as already remarked) six, eight, and sometimes ten or twelve inches deep; but as it is generally supposed that their residence is more profound, it is necessary to shew that this is an error, during their pupa state at least. To determine this question, and some others no better settled, we selected for our field of observation, an ancient oak grove of several acres. The upper stratum is a stiff loam, mixed with some gravel, and inclining, in places, to sand. At a depth of from two to three feet there is a stratum of pale blue