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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    and if they are travelling quickly (which they sometimes do), you experi- ence a disagreeable effect when they strike you on some tender part about the face. You will also perceive evident ocular demonstration of their presence and number from their “ droppings.” The dropping is about one-third of an inch long, and if the roof of the building or house in which you happen to be is of corrugated iron, when a swarm passes that has had a good feed previously, you will hear the effect of the droppings like great drops of rain. You can also see the droppings on the road or ground, but the effect is best seen if they happen to pass over where white linen is spread out on the ground to be bleached. 76. No fixed period for striking- their tents.—There is no fixed stated time of the year to a day or a week or a fortnight when the locusts can be said to commence their peregrinations to their temporary homes—that is, to wander and invade a country. Some seasons they appear earlier than they do at others. Probably their advent may have some bearing on climatic influences. Thus in a warm season they may come earlier if the heat be prematurely great and early, and vice versa. Thus, in the Argentine as in South Africa, the invading hosts may be noticed to appear as early as July or in August, or more often in October and November, and sometimes later in the summer. There is no stated fixed time that one would be safe in affirming for their appearance in any given locality. 77. Style of flight. —The height from the ground at which locusts fly varies. They travel in general at a height of from forty to four hundred feet, but they not unfrequently fly as high as five hundred to eight hundred feet or more, and under certain circumstances as high as two miles, when great distances or other unknown circumstances have to be overcome.1 It is said that the moon on a clear bright 1 Darwin, in his Researches, encountered locusts near Lujan, province of Mendoza, Argentine Republic, 1835, and says : “They appeared as a ragged cloud of a dark reddish-brown colour. For some time we had no doubt but that it was thick smoke proceeding from some great fire on the plains. Soon afterwards we found it was a pest of locusts.1 The insects overtook us, as they were travelling northward, by the aid of a light breeze, at the rate, I should suppose, of ten or fifteen miles an hour. The main body filled the air from a height of twenty feel to that, as it appeared, of two or three thousand above the ground. The noise of their approach was that of a strong breeze2 passing through the rigging of a ship. The sky seen through the advanced guard appeared like a mezzotinto engraving, but the main body was imper- vious to sight. They were not, however, so thick but that they could escape from a stick moved backward and forward. When they alighted they were more numer- ous than the leaves in a field, and changed the green into a reddish colour. T he swarm having once alighted, the individuals flew from side to side in any direction. The locusts are not an uncommon pest in this country. Already during the season 1 The species is identical with, or resembles most closely, the famous Gryllus migratorius of Eastern countries. 2 “ And the sound of their wings was as the sound of chariots of many horses running to battle (Rev. ix. 9). 3
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