349 
A MIGRATION OF COCKROACHES. 
By L. « >. Howard. 
It is a matter of common observation in main' of our more southern 
cities tbat new houses are often found to be suddenly overrun by cock- 
roaches and particularly by the little Croton bug or '-water bug" 
[Uctobia german ica ). The why and wherefore have been guessed at, but 
no definite observations are upon record. On a dark drizzly day in S«q>_ 
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. A few hours later I visited the spot in company with Mr. Mar- 
latt and found that the bulk of the army had disappeared, but that 
many stragglers still remained. Mr. Dorsett is an assistant in the 
Division of Vegetable Pathology, and according to his statement the 
army 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 lin3 of hot 
ashes from the furnace be laid along the brick sidewalk. This proved 
an effective barricade. The foremost cockroaches burned their 
anteume 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 Croton bug 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 effort 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 the 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. 
