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Order Diptera
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| Posterior abdominal segment without tubercles (t) other than those bearing spiracles. If present, prothoracic spiracles fan shaped and usually with less than 10 papillae. Oral sclerite (os) below mouth hook. |
Posterior abdominal segment often with several pairs of tubercles surrounding spiracles (s). Prothoracic spiracle (ptxs) a sievelike plate, or with many papillae arranged in a 2-horned fan. No oral sclerite. |