336 



noniic importance as enemies of wire worms, and it seems strange that 

 nothing has been pubHshed in America regarding this habit. 



In Europe several species have been reared, and all are credited 

 with being predaceous enemies of insects in the larval stage. A fairly 

 complete summary of the European investigations has been given by 

 Lundbeck in "Diptera Danica", Part 2 (1908), p. 137. In this paper 

 mention is made of the fact that occasionally the larvse of Thcrevidcc 

 may devour their own kind — a fact that comes within the knowledge 

 of the present writer from his experience in rearing Psilocephala, the 

 reason for the cannilialism being the lack of other food. 



MYDAID^ 



Mydas clavatus Drury 

 Musca clavatus Drury, Tllustratioiis of Natural History, Vol. 1, p. 103, 1770. 



Pupa (PI. LXXXII, Eig. 9). — Length, 36 mm. Reddish brown, 

 subopacjue. Surface of head and thorax coarsely rugose, that of ab- 

 domen rather finely and regularly rugose. Thorns of head rugose to 

 apices, lateral cephalic thorn as in Eigure 16. Eront of head as in 

 Eigure 10; lateral aspect as in Eigure 15. Thorax with a bifid humeral 

 tubercle, the one on wing-base with a single flattened thornlike process. 

 Eirst abdominal segment with the thorns (Eig. 21) directed forward 

 and located close to anterior margin, succeeding segments with the 

 thorns rather smaller, directed backward, and located caudad of the 

 transverse median line of the segments, the portion of each segment 

 caudad of the thorns declivitous and honeycombed, the anterior por- 

 tion irregularly rugose ; apical segment with 2 slightly curved proc- 

 esses which are a little upcurved (Eig. 8) ; spiracles as in Eigure 23. 



The specimen from which the .above description was drawn, was 

 obtained at White Heath, 111., May 26, 19 10, as a larva in a rotten 

 tree-stump, the adult emerged July 18, 1910 (A. G. Vestal). The 

 writer obtained a pupa under a rotten tree-stump at Kinderhook, 111., 

 in June, 1914. The laboratory collection contains imagines from the 

 following Illinois localities: Urbana, July 4, 1914 (Malloch) and 

 August 3, 1909 (Hart) ; Champaign, August 13, 1892 (Hucke) ; Al- 

 bion, July 12, 1888 (Marten) ; Havana, July 13, 1897 (Hart and 

 Brown) ; Alto Pass, August 2"/, 1889 (Hart) ; Pinkstaff, July i, 191 1 

 (Glenn); Monticello, July 2, 1914 (Hart and Malloch); Muncie, 

 July 5, 1914 (Hart and Malloch) ; and Bloomington, July 26, 1895. 



The specimens taken at Muncie were mostly captured on flowers of 

 milkweed, several being taken with the fingers — a proceeding which 

 generally results in the captor's discovering that the insect can pinch 



