I4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 134 
the electrical conduit system. Later when certain electrical junction 
boxes were opened they were literally packed with dead roaches. The 
migration occurred just prior to the first snowfall, and shortly after 
the city council decided to discontinue the use of an open dump.” 
Gould and Deay (1940) reported that specimens of Periplaneta 
americana have been observed migrating from restaurants and city 
dumps on several occasions. In one instance these cockroaches mi- 
grated during the summer from store buildings three blocks away 
and established themselves in decaying trees from which they entered 
homes. Alfieri (1920) reported an extraordinary abundance of this 
species in depots and warehouses in Egypt from which both nymphs 
and adults migrated into habitations, especially during the night. Sten- 
burg (1947) reported that inside treatment of houses with insecticide 
only partially reduced infestations of American cockroaches. But 
after an outside application of spray to incinerators, garbage disposals, 
garages, and outside lavatories, no further migrations into the treated 
buildings occurred. The Unionport section of the Bronx (New York 
City) has been “invaded” by hordes of flying cockroaches (Anony- 
mous, 1952). According to Dr. Ralph Heal (p.c.), these cockroaches 
were Periplaneta americana which swarm out of the sewers each year 
and appear in the streets and basements of adjacent buildings. 
Lederer (1952) for several years observed the Periplaneta ameri- 
cana that inhabited the zoo at Frankfurt am Main. The insects congre- 
gated in groups of 20 to 300 individuals in heated spaces. After dark 
they traveled extensively through the aquarium building in search of 
food, returning to their resting places by daybreak. During warm 
weather, the cockroaches spread to all parts of the building, but when 
cooler weather arrived they withdrew into heated areas. During 
warm, sunny days, individuals or small groups left the aquarium build- 
ing and migrated to nearby animal houses which they colonized. 
Dispersion from aquarium to animal houses apparently occurred only 
with an increase in the cockroach population and in warm weather. 
However, dispersal within the aquarium building could occur with a 
limited population. On these migrations between buildings, P. ameri- 
cana occasionaliy flew distances up to 30 meters in fairly straight 
courses or in flat arcs about 4 meter to 14 meters above ground. . 
Beebe (1951) observed a daytime migration of at least 30 indi- 
viduals of Blaberus giganteus (Linnaeus) through the pass at Rancho 
Grande, Venezuela, at an elevation of 1,100 meters. The insects were 
flying in a compact group at 10 o’clock in full sunlight. 
Kudo (1926) observed that at the University of Illinois, from 
March to November, Blatta orientalis crawled out of crevices at the 
