title: Scanning electron microscopy of the posterior spiracles of cattle grubs Hypoderma bovis and Hypoderma lineatum.
abstract: Posterior spiracles of newly hatched first instar larvae of Hypoderma bovis (L.) and H. lineatum (DeVill.) consist of two pairs of spiracular openings. Each pair is surrounded by a rima bearing three spines. Posterior spiracles of second instar larvae are composed of a pair of medial ecdysial scars bounded laterally by spiracular plates. H. bovis spiracular plates have twenty-nine to forty openings, each surrounded by a slightly raised rima. H. lineatum spiracular plates have eighteen to twenty-five openings. Spiracular openings lead to posterior felt chambers which are connected to a common anterior felt chamber filled with a meshlike network. In third instar H. bovis each medial ecdysial scar is surrounded by a strongly concave spiracular plate. Spiracular openings are surrounded by slightly raised rima. Most rimae bear a spine. Spiracular plates of H. lineatum are flat and rimae are without spines. Each spiracular opening leads to a posterior felt chamber, several of which are confluent with a larger anterior felt chamber. Anterior felt chambers open into the dorsal longitudinal tracheal trunk. Felt chambers in third instar larvae are also filled with a complex mesh.
authors.affiliation: Agriculture Canada Research Station, Lethbridge, Alberta.
authors.forename: D D
authors.initials: DD
authors.lastname: Colwell
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000469:parasitology; D004175:Diptera / Q000648:ultrastructure*; D007000:Hypodermyiasis / Q000469:parasitology / Q000662:veterinary; D007814:Larva / Q000648:ultrastructure; D008855:Microscopy, Electron, Scanning