GENERAL CHARACTERS. 13 



about 24 rather large eggs, while in southern Russia this fly deposits 

 a large larva in the first stage, which passes into the third stage 

 omitting the second stage. It may be that he has made a wrong 

 identification, but he claims to have been particularly carefid in this 

 matter. 



With the fruit-flies the eggs are deposited on or in the immature 

 fruit, the larva) feeduig on the pulpy substance till full grown, and 

 then crawling from the fallen fruit into the soil for })upation. 



CLASSIFICATION. 



The dipterous larvae that may be swallowed by man belong to 

 several families inchuletl in the old group of Muscid£e. These families 

 are the true Muscidse, Sarcophagidse, Anthomyiidse, and Trypetidse. 

 Other groups, as Drosophilidae, Sepsidae, and Ortalidse, are of much 

 rarer occurrence. The flies of the Ortalidae, Trj^petidae, and Sepsidae 

 are quite difi"erent from those of the other groups, but the adults of 

 the three other families are very similar in structure, and the limits 

 of the groups or the number of groups is not constant with difl'erent 

 specialists in Diptera. Some would separate a group known as the 

 Calliphorinse from the Muscidae; others make a special family for the 

 biting Muscidae (Stomoxjddae) . It is not the writer's purpose to 

 make any choice of the different plans, nor does he consider that 

 families should be defined by larval characters, but after the descrip- 

 tions of the several species a few words will indicate what sort of a 

 classification would result from a study of these larvae. The groups 

 used in the tabulation of the larvae are used only for the larvae and 

 do not indicate any opinions about the arrangement of the flies. 



There are other flies whose larvae are sometimes reported as swal- 

 lowed by persons, particularly the rat-tailed larvae of Eristalis, which 

 sometimes get into drinking water. 



GENERAL CHARACTERS. 



(See fig. 1.) 



The larvae of all these forms are broadest near the tip of the body, 

 and taper forward, more so in the true Muscidae than in the other 

 groups. The surface of the body may be smooth or scabrous, pro- 

 vided with minute, acute granules or teeth, or with short, stiff hairs. 

 With many forms there is on the anterior border of most of the seg- 

 ments a swollen ring or girdle; sometimes only on the ventral side. 

 In some cases there are other swollen areas, or pads, usually fusiform 

 in shape. 



The first segment, or head, commonly appears bilobed when viewed 

 from above, and each lobe bears a minute, cylindrical tubercle or 

 papilla (fig. 1, a). Below is the mouth aperture; at one side and 



