But are carriers of parasitic and infectious diseases ; > Lice — permanent ectoparasites of animals , causing sifunkulyatozy , accompanied by itching , peeling skin , hair loss , anemia and lower productivity ; > Fleas — temporary bloodsucking ectoparasites that cause itching , scratching , loss of productivity , and body weight gain . Estrosi sheep This invasive disease caused by the larvae of nasopharyngeal gadfly parasite in the nasal and frontal sinuses of sheep. Economic damage is expressed in decrease of meat , wool and milk production of sheep. Pathogen — gadfly of estrid family , which are characterized by starvation ( state Afaq phase pupae and adults ) , multiple pregnancy and live birth .
12-20 days after fertilization in the genital tract of females mature between 240 and 600 larvae. Female on the fly injects into the nasal passages of sheep 6-12 larvae. I stage larvae develop in the mucosa of the nasal turbinates and bone lattice larvae stages II and III — in the frontal sinus cavities and horny shoots.
Larvae injure the mucosa , causing its inflammation and necrosis . Once on the surface of the soil , the larvae burrow into stage III and pupate . At a temperature of 17 ° C after 18-32 days from the pupa imago leaves ( Fig. 21 ) . 2-3 days mating takes place , after which the males die and the females get into the gap buildings , trees, and there are 2 weeks ( before maturing larvae in the genital tract ) .
In temperate climates, the duration of generation is about 11 months . Duration summer gadfly — 15-18 days. Fig . 21. Gadfly Oestrus ovis: 1 — female larvae stage 1 ; 2 — emergence of adults from pupae ; 3 — gadfly larvae in the cavity of the head sheep Source invasion — Estrosi sick sheep .
Mass disease occurs in spring and summer.