Cuticular sensilla on newly hatched larvae of Gasterophilus intestinalis and Oestrus ovis.

Cuticular sensilla on newly hatched larvae of Gasterophilus intestinalis De Geer (Diptera: Gasterophilidae) and Oestrus ovis (L.) were studied by scanning electron microscopy. Two types of trichoid sensilla, two types of coeloconic sensilla and a pit sensillum were present on the thoracic and abdominal segments of G.intestinalis larvae. Sensilla on larvae of O.ovis were similar although only one type of trichoid sensillum was present. Total number of sensilla were higher for O.ovis than for G.intestinalis (248 v. 214). Variation in numbers of sensilla is consistent with the concept that increasing numbers of sensilla are associated with increasingly complex searching behaviour required to locate suitable habitats for development.