196 NORTH AMERICAN DIPTERA. 



thorax of the male, carried them both off together. The 

 larvae live for the most part in rotting wood, under bark, 

 or in soil containing decomposing vegetable matter, un- 

 der leaves, etc., and feed upon grubs and other larvae. 

 The larvae are cylindrical in shape, with parchment-like 

 skin, the abdominal segments sometimes girdled with 

 rounded tubercles, or with abdominal protuberances for 

 locomotion, The pupae are free, with strong booklets 

 at the anterior end, the abdomen provided with spiny 

 girdles, mixed with hairs below and behind; the last seg- 

 ment has two short, divaricate booklets and several 



■aller projections. 



i he young larvae sometimes bore their way completely 

 within the bodies of other larvae, remaining there till 

 their food is wholly consumed. Often the larvae are 

 found free in the earth, however, where their transforma- 

 tions occur. The eggs are laid about grass stems, or in 

 crevices of decaying logs and trees infested by the larvae 

 of other insects. 



The division of the family into four subfamilies based 

 upon the closure or non-closure of the marginal cell, and 

 the presence or absence of a terminal bristly arista is ar- 

 tificial in a large measure, but at the same time is very 

 useful. I also doubt the importance of the terminal spur 

 on the front tibiae as a true index of relationships. So 

 far as my studies go, the structure of the palpi is a more 

 natural character for subfamily division, the Dasypogo- 

 ninae and Laphrinae having two joints, the Leptogas- 

 trinae and Asilinse one. The Leptogastrinae are, further- 

 more, entitled to subfamily distinction because of the 



front; 37 ■, Stenopogon [Scleropogon) truquti, head; 58, Archilestris 

 magnijicus, head; 39, Chrysoceria pictitarsis, head; 40, Dizonias, sp. 

 bead; 41, Pseudorus bicolor, head; 42, Atonia mikii, head; 43, Ato- 

 tnosia macquartii, antenna; 44, Ceroiainia, species, antenna; 45, 

 Lavtpria, species, hind leg; 46, Laphria (JVusa), sp. , wing. 



