IU JOURNAL, BOMBAY NATURAL BISTORT SOCIETY, Vol. XV. 



West Locust (Acridium peregrlnum of India) and the Rocky Mountain 

 locust (Melanoplus spretus of North America), Insects which at times 

 swarm in millions and clear the country they invade of every green 

 thing. Every leaf is stripped from the trees, every blade of grass 

 consumed and fields of crops eaten down as the flight moves onwards, 

 leaving devastation and ruin in its wake. There are many species of 

 Acridiidse in India, and many of them at different periods swarm 

 and do damage, but the North-West or migratory locust is the only 

 one which entirely overruns the country when on one of its great 

 incursions. "We will consider shortly the life-history of Acridium 

 peregrinum. 



The home of this locust is in the sandy deserts of Rajputana and 

 Sind, from which it periodically invades the whole of India, The eggs 

 are laid in the ground and hatch out in about a month, but two months 

 or a much longer period may be spent in the egg stage if conditions are 

 not favourable to the young ones hatching out. The young are little 

 blackish wingless grasshoppers, which feed upon green plants of all kinds. 

 (See Frontispiece.) At the end of the first five days after hatching the 

 young locusts or 'hoppers' pack together and march in serried columns 

 into the fields and begin their work of devastation. This stage lasts from 

 one to two months, during which time the insects moult their skins at 

 intervals. Their wings develop during these several moults, and the 

 last shedding of the skin leaves the Insect with perfectly developed alar 

 appendages. As soon as they are full-grown, the locusts quit the areas 

 which they have occupied during their younger stages and 

 from which they have by then eaten everything green, take 

 wing and fly to fresh districts, which they proceed to devas- 

 tate in a similar manner. After a week or two spent in 

 these wanderings the insects pair and the females commence 

 egg-laying in the soft soil of the cultivated lands, as many 

 Fig. 15. as 100 eggs, stuck together in a mass with some siccable sub- 

 stance, being deposited by each insect. Fig. 15 shows the eggs laid 

 by one locust and the shape of the mass. At the egg-laying period 

 they cease feeding or only take a small amount of food, and for this 

 reason are often reported in telegrams, crop reports and newspaper 

 accounts as doing little or no damage. Closer observation would show 

 that they are egg-laying, and the young hoppers hatching from those 

 eggs will later on cause infinitely more destruction in the area than the 

 swarm themselves would have been capable of. 



