Observations of the effects of formaldehyde on cockroaches and their flora: III. The effect of formaldehyde in eliminating the normal gut flora.

The normal flora of cockroaches (Periplaneta americana) was determined over a period of 24 days prior to substituting water with 1% Formalin for drinking water. During the first 4 days of treatment the normal flora was significantly reduced and by the fifth day, when the cockroaches became diarrhoeic, no bacteria, fungi, or viruses could be detected by the methods used.