397 



dorsal extension in the form of a single stout rod with spatulate apex ; 

 mandibles strong, deflected in front and pointed at apices; antennae 

 of moderate length (PI. LVII, Fig. i). Prothoracic spiracle distinct 

 (PI. LVI, Fig. 9) ; each thoracic segment with 2 hairs, one on middle 

 of the latero-ventral line on each side. Abdominal segments 1 to 6 

 divided by means of a distinct circular constriction, so that the body 

 appears to consist of 20 segments; posterior spiracles on antepenulti- 

 mate abdominal segment ; ultimate segment with 2 short points at 

 apex and several surface hairs. 



Pupa (PI. LVI, Fig. 12). — Distinguishable from other pupae of 

 the Brachycera by the presence of 2 thorns (antennal sheaths) on head 

 and a long curved thorn at base of each wing. The abdomen has a 

 single girdle of thorns on each segment, and the apical segment ends 

 in 2 long, slender. thorns which are contiguous except apicallv (Fig. 



13)- 



Imago. — See key to families of Brachycera. 



HABITS OF LARVAE 



The larvae are found in the ground and also in decaying wood. 

 I have found one species in wheat fields and in woods. They are 

 predaceous, feeding upon various insect larvae, including wireworms, 

 and under conditions of overcrowding or scarcity of other food they 

 are cannibalistic. 



HABITS OF IMAGINES 



The flies are very active, especially during sunshine, when they 

 may be found frequenting bare paths and sandy or exposed banks. I 

 have no data upon their food habits except that they frequent flowers 

 occasionally. 



I have no record of parasitic enemies of any stage. 



Psilocephala haemorrhoidalis Macquart 



Thereva haemorrhoidalis Macquart, Dipt. Exot., Vol. 2, Pt. I, p. 26. Imago. 



(1841) # 

 Psilocephala haemorrhoidalis Macquart, Malloch, Bull. 111. State Lab. Nat. 



Hist., Vol. 11, Art. 4, p. 334. Larva and pupa. (1915) 



This species is the only Psilocephala that I have found in Illinois 

 in the larval stage, although a number of other species of the genus 

 are well represented in our collection of imagines. The habits are 

 as previously mentioned for the family ; descriptions of all stages are 



