ORTHOPTERA. 307 
Tn the environs of Algiers alone were destroyed, in 1845, 369 
quintals of locusts. It is computed that four hundred locusts go 
toa kilogramme. ‘This gives, then, a total of 14,760,000 insects 
destroyed. As in this number half were probably females, and as 
each female lays on an average 70 eggs, the result we arrive at is, 
that this stopped the production of 516,600,000 larve on the 
territory of Algiers alone. The invasion of locusts which took 
place in 1866 was as disastrous as that of 1845. It was in the 
month of April, 1866, that the vanguard of these destructive 
insects appeared. Debouching through the mountain gorges and 
through the valleys into the fertile plains near the coast, they 
alighted first on the plain of the Mitidja and on the Sahel of 
Algiers. Their mass, at certain points, intercepted the light 
of the sun, and resembled those whirlwinds of snow which, during 
the storms of winter, hide the nearest objects from our view. 
Very soon the cabbages, the oats, the barley, the late wheat, and 
the market-gardeners’ plants were partly destroyed. In some 
places the locusts penetrated into the interiors of the houses. By 
order of the government of Algiers the troops joined the colonists 
in combating the plague; and the Arabs, when they found that 
their interests were suffering, rose to lend their aid against the 
common enemy. Immense quantities of locusts were destroyed in 
a few days; but what could human efforts do against these winged 
multitudes, who escape into space, and only abandon one field to 
alight in the next? 
It was impossible to prevent the fecundation of these insects. 
The eggs quickly producing innumerable larve, the first swarms 
were very soon not only replaced, but multiplied a hundredfold by 
a new generation. The young locusts are particularly formidable 
on account of their voracity. These hungry masses threw them- 
selves upon everything which was left by those which went before 
them. 'They choked up the springs, the canals, and the brooks ; 
and it was not without a great deal of trouble that the waters were 
cleared of these causes of infection. Almost at the same time the 
provinces of Oran and of Constantine were invaded. At Tlemcen, 
where within the memory of man locusts had never appeared, 
the ground was covered with them. At Sidi-bel-Abbes, at Sidi- 
Brahim, at Mostaganem, they attacked the tobacco, the vines, the 
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