8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 134 
becomes a pest in supermarkets, but is of minor importance when 
compared with the other two species. 
Mallis (1954) described conditions in a four-room apartment in 
Austin, Tex., in 1947. The cockroach population was estimated to 
be 50,000 to 100,000, mostly Blattella germanica. These insects were 
killed with an insecticidal spray, but within six months it was esti- 
mated that 15,000 to 25,000 German cockroaches had again established 
themselves in the apartment. Mallis (1954) also reported finding 
approximately 280,000 cockroaches in 177 apartments examined in 
four cities in Texas in 1947. Over 99 percent of these were German 
cockroaches. 
Current literature on insect control indicates that, in spite of modern 
insecticides, cockroaches are a continuing problem in food-handling 
establishments: dairies (Adams, 1947; Gerlach, 1947; Gould, 1946) ; 
bakeries (Vincent, 1949); food and meat packing plants (Burke, 
1944; Parker, 1948; Somers, 1951); mess halls and restaurants 
(Carpenter, 1944; U.S.P.H.S., 1952). Even food plants with an 
adequate sanitation program report new invasions of cockroaches 
from time to time (Clark, 1954). 
Although there are specific differences in their behavior, many 
cockroaches show relatively little discrimination in their choice of 
food and habitat. This does not imply that all species are found in 
exactly similar locations, but only that all domesticated species may 
be found in both clean and dirty habitats, the latter being those in 
which disease organisms may be acquired. For example, cockroaches 
indiscriminately eat both the food and the feces of man and domestic 
and other animals. By feeding first on infected feces and later on 
food, cockroaches may readily effect the transfer of enteric parasites 
from animal to animal by the fecal-oral route. 
Although Jennings and King (1913) reported that cockroaches 
will not readily feed on fecal material, other observers have found 
otherwise. Barber (1914) stated that in his experiments, Periplaneta 
americana ate human feces readily. Porter (1930) stated that fecal 
matter is highly attractive to cockroaches. Human feces were ap- 
parently the sole food of P. americana in mines in western Bengal 
(Chandler, 1926). Jung and Shaffer (1952) found experimentally 
that P. americana ingested about 0.1 gram of human feces at a single 
feeding. A photograph showing Periplaneta americana apparently 
feeding on human feces in a sewer manhole is shown in plate 4. These 
examples could be multiplied, but there is no doubt that cockroaches 
will eat feces on occasion and become carriers of pathogenic viruses, 
bacteria, and protozoa (see appendices). In fact, in nature it is only 
