The locust plague and its suppression / by Æneas Munro.

  • Munro, Aeneas.
Date:
[1899]
Catalogue details

Licence: Public Domain Mark

Credit: The locust plague and its suppression / by Æneas Munro. Source: Wellcome Collection.

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    mechanism is for the object. Locusts, like all insects, never breathe through the mouth, but through the aforesaid spiracles, which are extensively distributed over the body, and thus their bodies are very highly charged with air or gases. 97. Circulation .—The circulation of the blood is carried on by a tubular vessel which serves as a heart, and which is best seen in the abdomen. It is a contractile chamber, and the flow of blood is regulated by its dilatation and contraction. There is no heart proper, and except in the tube mentioned the fluid that circulates is more lymph than blood. 98. Genital organs.—But by far the most interesting part in the anatomy of the locust is that which deals with the organs of generation, especially that of the female locust. The organs of both male and female are situated at the extreme tip of the abdomen and near the dorsal or superior surface, but a description of this wonderful function and the corresponding organs, particularly those in the female, will be found later on, when we deal with the nesting or laying. “ PAIRING ” 99. Locusts both “polyandrist” and “polygamist.”—The next interesting event about our flock of visitors is the “pairing.” The law or rule among the locusts seems to be similar and like that among birds. There seems to be one female for every male, and vice versa. They pair. This event occurs in a period of five or six weeks after they make their first appearance in or invade a locality. Inasmuch as it may not be the same company which first appeared in the district that now pair in it, of course no definite time can be stated as to when the event comes off, nor what is the age of the locusts that engage in this operation. When it takes place there is no difficulty in observing it. The whole company are engaged in this process, and more or less at the same time. It lasts only as a rule for a day or two. Of course they move little at this time, and only by a series of jumps made by the female—-the male being fixed and quiescent above her. By walking among them at this period you can catch them with ease. Indeed, this would not be a bad time—or at least it is one of the times—to attack and destroy them, as we will afterwards see. Thejengagement, in which the female receives the marked and deliberate attention of the male, lasts at least hours—more probably the whole of the livelong sunny day—and is concluded quietly and systematically. The operation passes on simultaneously through the whole band in about a couple of days, as if in obedience to the example set by the neighbours. When these attentions are over, the parties seem to take up their former place in the company, and dance about and do everything as
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