Abstract
A facility for the mass rearing of sterilized screwworm flies used in fly eradication program efforts was described. Air concentrations of formaldehyde and ammonia were measured during industrial hygiene surveys conducted in the production plant which is currently the world's largest insect rearing facility. Formaldehyde, used as a bactericide and fungicide in the larvae media, was consistently found at levels below current and recommended TLVs. Ammonia, released as metabolic waste from the larvae, was occasionally found at elevated levels in some plant areas. Factors were identified which influenced the in-plant variations of ammonia air levels.