50 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
In this connection we may add that Diodorus Sicnlus says "the west, 
north, northwest, and east winds blow in Ethiopia as in other parts of 
the world; but the south winds never blow, nor are ever known in 
Ethiopia" 117 . 
The visitation of Algiers by these pests in I860 was so severe that it 
drew a special official circular from Marshal Canrobert. They first ap- 
peared during the month of April, coming from the gorges of the moun- 
tains and the fertile valleys of the Littoral. They descended first on 
the plains of Mitidja and the Sahel of Algiers. Their mass at certain 
points intercepted the light of the sun, and produced an effect similar 
to that of the snow storms which in the winter season fall in Europe and 
blot out even the nearest objects from the sight. They deposited eggs 
which soon gave life to innumerable larvae, so that the first swarms were 
soon replaced and centupled by new generations. They not only de- 
stroyed all vegetation, but filled up the water-courses, the canals, and 
the rivulets, so that the troops had the greatest difficulty in preserving 
the water from infection. Almost at the same time the provinces of 
Oran and Constant ine were invaded at Heman, where no locusts had 
appeared within the memory of the oldest inhabitants. At Sidi-bel- 
Abbis, at Sidi-Brahim, and at Mostaganen they attacked not only the 
tobacco plantations, the vines, and the fig trees, but also the olive trees, 
notwithstanding the bitterness of their leaves. At Belizabe and at 
Harba they invaded the cotton grounds. In the province of Constantino 
the locusts appeared simultaneously from the Sahara to the sea, and from 
Bougie to Calle m . 
M. Girard 119 gives a very interesting account of this invasion, in which 
he says the opinion most generally accredited in reference to Acridians 
(locusts) of Algiers is that they come from the equatorial regions of 
Africa, from Soudan. That the swarms hatching in the sands of these 
regions — a part of which move to the south, the others to the north — 
those moving northward arrive by steps in the Tell of Algiers. The 
specimens of this swarm which were sent to the society, in all stages 
of growth, when examined proved to be A. perigrinum. 
Eeference to the species which is found migratory in Algiers and 
other parts of Africa, and its specific charaeteristics, will be found in 
various works. 120 
The most complete account of the natural history and ravages of this 
species in Algiers is by M. G. Lallemant. 121 He says the two great in- 
vasions, that of 1864 and of 1866, arrived in the month of April. That 
these insects inhabit all the North of Africa, and a part of Asia ; that 
"'Booth's Trans., i, 189. 
118 Trans. Ent. Soc, Lond., 1866, vol. v, Proa, xxiii. 
»»In Ann. Soc. Ent. France, 4th Ser., 1864, vii, BulL, x-xiii. 
™>Oliveer, "Voyage dansl'emp., Othom."ii., p. 424.— Servittt, "Orthop." 666.— Shaw, "Travels in Bar- 
bary and the Levant." — Poiret, Voyage en Barbarie, i, 306. — Compte-Bendu, Acad, des Sci., 1845, pp. 1041 
and 1499.— Lucas, "Explor. Scient. Alg.," in Scien. Phys. Anim., art. iii, 29, and Bull Soc. Ent France, 
1845, xxxii. 
ui In Ann. Soc. Ent. Big., voL 9. 
