349 . 



A MIGRATION OF COCKROACHES. 



Jiy L. ( ». Howard. 



It is a matter of coiuinoii observation in many of our more southern 

 cities that new houses are often found to be suddenly overrun by cock- 

 roaches and particularly by the little Crotou bug or "water bug" 

 {Ectobia (jermanica). The why and wherefore have been guessed at, but 

 no detinite observations are ui»on record. On a dark drizzly day in tSep. 

 tember, 1893, Mr. P. H. Dorsett came to me and stated that he had just 

 .seen a remarkable sight on D street, near the Department grounds. A 

 vast army of cockroaches, according to his story, was crossing the 

 street. \ few hours later I visited the spot in comi)any with Mr. Mar- 

 latt and found that the bulk of the army had disappeared, but that 

 many stragglers still renmined. ]\Ir. Dorvsett is an assistant in the 

 Division of Vegetable Pathology, and according to his statement the 

 array issued from the rear of an old restaurant fronting upon Pennsyl- 

 vania avenue and marched across the muddy street, undeterred by pools 

 of water, ash heaps, and other barriers, directly south to the front of 

 the budding opposite. 



This building was a machine shop and at the direction of the fore- 

 man several of the men took brooms and swept back the advancing 

 horde. They swept until their arms were tired, but were unable to 

 stem the advancing tide. The foreman then directed that a line of hot 

 ashes from the furnace be laid along the brick sidewalk. This proved 

 an eftective barricade. The foremost cockroaches burned their 

 antenna? and their front legs and the army divided to either side and 

 scurried down into the area ways of adjoining buildings in which they 

 disappeared. The march is said to have continued for two or three 

 hours and many thousands of the insects crossed in this way. A 

 moment's glance, after arriving at the spot, showed me that the insect 

 was the Crotonbug and that nearly all of the individuals were females 

 carrying egg-cases. 



I called at the restaurant and found to my surprise that no house 

 cleaning had been going on and that no especial eftbrt had been made 

 by the application of insecticides to rid the establishment of the 

 roaches. 



It seems then to have been a true migration, a development of the 

 true migratory instinct in the Croton bug. The restaurant had become 

 overpopulated, perhaps not for its actual denizens, but certainly for 

 the thousands of about-to-be-born young. The maternal instinct 

 originated tlie migratory instinct and the army by one common impulse 

 started on its journey 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. This is the way that new houses become 

 infested. 



