EN
Females and males of the house fly were exposed for 2 hr. on filtration paper impregnated with acetone solutions of gamma HCH in six dilutions according to geometrical progress with 2 as the multiplier and dried. Next the insects were transferred to clean jars, food was given and they were placed in thermostates at the temperatures 20, 25, 30, 35°C at the relative humidity 60% ± 5%. The results were recorded after 24 hours. It was observed that: 1) with the increase of the temperature of the surrounding followed an increase of the percentage of dead females and males, 2) there is in males a greater susceptibility to gamma HCH that in females, 3) there is a more marked increase of susceptibility to gamma HCH in females than in males with the rise of the temperature of the surrounding.