MIGRATION AND DISPERSAL OP INSECTS '. ORTHOPTERA. 45 



This species also is especially troublesome in some years in Mesopo- 

 tamia, where it usually occurs in April, the swarms appearing to come 

 from the south-east, probably having their origin in "southern 

 Persia or Beloochistan, or even still further east. Terrible damage 

 was done in Madras in 1878 and in the Deccan in 1882-88 by the 

 same species of locust, and north-west India suffered heavily from 

 another attack that took place in 1889. As is well known, the French 

 Government has taken considerable pains to cope with the locust 

 plague in Algeria. Great swarms of locusts, sufficiently numerous to 

 darken the sun in many places, appear to come from the edge of the 

 Sahara, or even across the Sahara from the Niger valley, whence 

 clouds are frequently reported. 



Writing of the invasions of Algeria by Schistocnra pcnyrina, Finot 

 says that this species arrives in the south of Algeria, in the' adult stage, 

 in early spring (from February to May). The SAvarms come from the 

 Sahara, and are generally brought by tlae sirocco or southern wind. Most 

 probably they come from certain parts of the Soudan, where drought 

 has prematurely destroyed their natural food. It has been observed in 

 Algeria that the immigrating swarms fly only l)y day, settling before 

 sunset, continuing their journey the following morning, and so on, 

 until they reach a favourable place for settlement or occupation, 

 choosing as a rule localities that are warm and rather humid. Here 

 they lay their eggs, the period of oviposition lasting about twelve days. 

 The eggs of the earliest swarms hatch from about April loth-May loth, 

 and, when the hatching period is completed, the young ones move off in 

 swarms of many millions, spreading out during the day for food, and 

 collecting together again at night. They now set off on their walking 

 tour towards the north, following this direction with amazing con- 

 stancy, and turned aside only by the greatest obstacles. During the first 

 days of this movement they only travel a few hundred metres a day ; 

 about the 15th day, however, they complete quite a kilometre, and, 

 after 35 days, when they have almost reached the adult stage, they 

 travel from four to five kilometres per day. On the average, dependent 

 on food and weather, such a body of wingless locusts travels from 

 30-50 kilometres. As the young ones become stronger, the front of the 

 column is considerably increased ; sometimes, however, the mass is 

 divided into many parallel marching columns. The depth of a swarm 

 often amounts to a league. About 40 days after the hatching period 

 the insects reach the adult stage. Their depredations now become 

 much more serious, as their powerful wings help them to overcome ob- 

 stacles previously impassable, and at this time of the year, towards the 

 end of July, herbaceous vegetation is becoming dried up and rare. 

 Spreading out each day for food, they return at night to a common 

 ground, until the stragglers have completed their last moult. Food 

 being scarce, they now fly high up into the air, and, after wheeling 

 round, appear to take their flight towards the south. 



Many authors have dealt with the migration of this species more or 

 less minutely, c.r/., Kiinckel d'llerculais, Lestage, Burr, &c., but the 

 details are too extensive to be more than noted here. 



^OLEOPTERA. 



CoLEOPTERA IN THE HASTINGS DisTKicT. — During thc past season 



