Ultrastructures of the Larval Cephalic Sensory Organs of the Onion and Seed-Corn Flies, Hylemya antiqua MEIGEN and H. platura MEIGEN : Diptera : Anthomyiidae

The ultrastructures of the dorsal, anterior and ventral organs of the onion fly larva Hylemya antiqua MEIGEN and the seed-corn fly larva H. platura MEIGEN were investigated using scanning and transmission electron microscopes.The dorsal organ consisted of 7 sensilla classified into 4 types. The dome part was considered to have olfactory function, since the cuticle had many canal-like structures which connect the inside and the outside. The 3 sensilla between the dome and the socket were considered to be mechanosensory or gustatory. The functions of the other 3 sensilla, 1 in the invagination of the socket and 2 between the dome and the socket, were not clear. This organ was assumed to have mainly olfactory function.The anterior organ consisted of 13 sensilla classified into 5 types. Among them, 10 sensilla of 3 types were considered to have gustatory function. The functions of the other 3 sensilla were not clear. This organ was assumed to have mainly gustatory function.The ventral organ consisted of 4 sensilla classified into 3 types. Two types were considered to be mechanosensory, however the function of the remaining one was not clear. This sensory organ was considered to contain no chemosensillum.No difference was found in the structures of these 3 sensory organs between the onion fly and the seed-corn fly.