抄録
External morphology and function of sensory organs on the head of the onion fly larva, Hylemya antiqua MEIGEN were investigated. Three pairs of sensory organs were present on the cephalic lobe of the onion fly larva when observed with a scanning electron microscope. A dome-shaped organ (diam. 15-17 μm) with a little peg was at the dorsal part, a set of 8 peg-like sensilla (diam. 2-5 μm) at the anterior part, and a plate-type organ and a lobe with a peg at the ventral part.Functions of the dorsal and anterior organs were examined by cauterization with a sharp-tipped hot iron pencil. The larvae cauterized at both or either one of the dorsal and ventral organs could not orient towards the host plant onion and their trails became random, although their movement activity was little affected. From these results, we concluded that these organs had a chemosensory function and were indispensable in pairs for perception of and orientation to the host plant.
