Fortunately, these concerns were unfounded as revealed by the successful field experiments
conducted in Costa Rica. Waste reduction exceeded all our expectations despite local stumbling
blocks, such as a fly colony weakened by zinc poisoning and a far lower larval density. Instead of
waste reduction values around 40% as achieved in the laboratory, the household waste could be
reduced from 65% to 75% (Table 1). Even the prepupal weight attained under field conditions was far
higher than the value assessed in the laboratory. Prepupae grown on municipal organic waste
weighed 195–220 mg (wet weight) – even prepupae fed in the laboratory experiments with the highest
waste ration weighed 25% less (157 mg).