332 Life stories of Australian insects. 



tubercles are retained (Plate 44, Fig. 8) ; (b) when 

 the puparium shrinks and forms a smooth, barrel- 

 shaped, seed-like appearance — example, fruit flies, 

 house flies, etc. (see Plate 40, Fig. 3). In many 

 cases the pupa is free, having no larval skin present 

 to form a puparium, examples: tipulids (''daddy- 

 long-legs") (Plate 42, Fig. 3), march flies, sand 

 flies, robber flies. 



The Order Diptera includes both friends and 

 enemies to man. The tachinids, sarcophids, 

 syrphids parasitise other insect pests; but, on 

 the other hand, there are many disease-producing 

 dipterous insects. The mosquitoes infect man with 

 fever, such as malaria and yellow fever; and house 

 flies carry germs of typhoid, anthrax, etc. 

 The tsetse fly infects cattle with '' fly disease, " 

 and Glossina transmits to man the ''sleeping sick- 

 ness." "Blow flies" cause meat to be unfit for eat- 

 ing, and some species attack the soiled wool and 

 afterwards tlie flesh of the sheep, the maggots feed- 

 ing on them. The "hot flies" include serious pests 

 whicli attack liorses, cattle, and sheep. Then the 

 "fruit flies" destroy the orchard crops. 



FAMILY CECIDOMYID.E. 



(Gall Gnats.) 



Tliese are very minute flies with wings witli few 

 veins. The antennae are long, with whorls of hairs. 

 Tlic larva? are plant-eaters, attacking roots, stems, 

 or leaves. Some make malformations on plants, 

 known as "galls." The "acacia gnat" (Cecidomyia 

 acaciae-longifoliae) lays numerous eggs in the 



