Development of the nematode eyeworm, Thelazia skrjabini (Nematoda: Thelazioidea), in experimentally infected face flies, Musca autumnalis (Diptera: Muscidae)

The development of Thelazia skrjabini Erschow, 1928, was studied in experimentally infected laboratory-reared Musca autumnalis De Geer. Thelazia skrjabini developed to the infective third stage in a minimum of 9 days in M. autumnalis maintained at 27 +/- 2 C. First-stage larvae were not observed postinoculation, but second-stage larvae were first observed 3 days postinoculation. Development was asynchronous. Second- and third-stage larvae occur in capsules, occasionally in the head but primarily in the abdomen attached to fat bodies. First-stage larvae have anteriorly 1 ventral and 2 dorsal hooks, directed posteriorly. Second-stage larvae have 4 submedian cephalic papillae and faint annular striations. Third-stage larvae have 6 labial papillae, 4 submedian cephalic papillae and pronounced annulations. Morphometric studies of each larval stage were performed with specimens in glycerine.