LABORATORY STUDIES ON THE CHEMO-SENSORY REACTIONS OF BLOWFLIES

Attraction of various blowflies to sheep wool has been demonstrated under laboratory conditions using a choice-chamber technique. The attractive factor in wool is intimately associated with the wool fibre for it does not disappear during storage and it is not completely removed by washing. Only female flies were attracted to wool. The highest degree of attraction was obtained from fertilized females which had daily access to meat. Even in the absence of fertilization and meat, attraction was not completely abolished. The species and strains tested can be placed in the following order in terms of strength of response to sheep wool : Lucilia sericata (British), L. cuprina (tested on damp floor) > L. sericata (Danish: country) > L. sericata (Danish: city), L. sericata (Australian) > L. illustris, L. caesar. No response was given by Calliphora vomitoria. The olfactory organs involved in the response to wool are mainly on the antennae but antennaeless L. sericata and L. cuprina with some tarsi removed were still able to show some response to wool provided that they were tested on a damp floor. In the course of testing the olfactory responses it was also shown that the main humidity receptors are present on the antennae. The existence of a 'wool-factor' to which only certain strains of L. sericata and L. cuprina are specially sensitive offers a possible explanation for the greater efficiency of these species as myiasis-producing forms.