120 THE entomologist's record. 



crickets having been swept into the gutters, both here and at Fort 

 "Worth, they produced a nauseating stench. Gilbert White records an 

 invasion of a house by a swarm of (injlltis (hniK'sticits, which they 

 entered from all quarters, flying with an undulating flight like that of 

 some of our small birds. 



In concluding our notes on the migration and distribution of the 

 Orthoptera, we may mention the oft-repeated observation of the move- 

 ments of cockroaches from house to house. One of these was detailed 

 {Insect Life, vii., p. 349) by Howard, at length. He states that in 

 September, 1893, a vast army of I'liyllodromia f/eniuaiica was observed 

 crossing the street (? at Washington) on a dark drizzly day. The army 

 issued from the rear of an old restaurant fronting upon Pennsylvania 

 Avenue, and marched across the muddy street, undeterred by pools of 

 water, Sec, to the front of the building, a machine shop, opposite. The 

 men vainly attempted to sweep back the cockroaches with brooms, and 

 at last laid a line of hot ashes along the side Avalk, this proving an 

 effective barricade. The cockroaches were diverted, and at once 

 entered the adjoining buildings on either side. It is said that the 

 march continued for two or three hours, that many thousands of insects 

 crossed in this way, and that nearly all the individuals were females 

 carrying egg-cases. Enquiry at the restaurant elicited the information 

 that no special means had been taken to get rid of the insects, and Howard 

 presumed, therefore, that it was a case of true migration, due to the 

 over-population of the restaurant, whose resources could no longer 

 support the prospective increase of the about-to-be-born young. He 

 supposes that " the maternal instinct originated the migratory instinct, 

 and that the army started on its journey at once for more commodious 

 quarters. The darkness of the day is significant, and there is no 

 reason to suppose that similar migrations do not frequently occur, but 

 undoubtedly, under ordinary circumstances, at night." He adds that 

 " this is the way that new houses become infested with cockroaches." 



It were easy to fill a volume with records similar to these, which must 

 be taken merely as a fair sample of a much greater number. Enough, 

 however, has been written to show how frequently swarms of these 

 destructive insects have been observed. It appears probable, from the 

 evidence offered by the various records, that erratic as the movements 

 of "locusts" generally are, their migrations are more or less directly 

 connected with food-supply, that they are indeed foraging expeditions, 

 and, so far as any return to the land from whence their ancestors have 

 come takes place, it appears to be equally due to dispersal in search of 

 food. The Algerian visitations show this. They arrive in an adult 

 state from the parched south when vegetation is at its best in Algeria, 

 the immigrants lay eggs, and the young find an abundance of food. 

 These become adult in July, just as the country that has reared them 

 becomes parched and the vegetation dried up. Then they are said to 

 fly south again, possibly to lands that are now fitted again to support 

 another brood, although it must be confessed that much more exact 

 evidence as to these reputed return swarms is needed. Our knowledge 

 of the "return swarms," mentioned in relation to the American 

 species, is also most unsatisfactory, and is so ill-defined that general- 

 isations on the information at hand are almost impossible. 



It would appear to us that in certain districts, which are the real 

 sedentary honie of the migratory species, normal conditions of food, 



