206 MAINS AGRICULTURAL EXPERIMENT STATION. 1916. 



in opposite directions, either resting or the male being passively 

 dragged about from leaf to leaf by the female (Temno stoma). 

 The process of copulation has been observed to continue for 

 many hours at a time. 



The next and final step in the completion of the life-round 

 or life-cycle is oviposition for the next generation. The female, 

 no longer closely attended by the male, hovers about the medium 

 on which the larvae are to feed settling down at intervals to 

 place the eggs. The terminal segments of the abdomen with 

 the ovipositor are greatly extended and the egg passes between 

 the vulva to its position on leaf, filth, or other medium, accord- 

 ing to the habits of the particular species. The eggs may be 

 placed singly and greatly scattered, as in most of the predaceous 

 species ; or several may be placed closely side by side 

 (Melanostoma mellinum, q. v.) ; or they may be deposited in 

 great numbers in a mass, as in most of the filth-inhabiting 

 species. In the latter case some of the species seem to rank the 

 eggs in quite regular order ; in others they appear to be simply 

 extruded in a pile with little regard to their orientation. Often 

 a gluey substance is passed with the egg which fastens it securely 

 to some surface. Eggs succeed each other commonly at inter- 

 vals of about a minute. 



Habits of the Larvae. 



The habits of the larvae of Syrphidae, which are remarkably 

 varied, have formed an interesting subject of study for a num- 

 ber of years. Perris in 1870 (41) gave a brief resume of the 

 modes of life of these larvae as known to him. Williston, 1886, 

 (62, p. 271), Verrall, 1901, (55, p. 674) and the writer, 1913, 

 (35, pp. 38-42) have amplified and extended this table to include 

 additional habits and species as determined. 



I have attempted to outline our present knowledge of the 

 habits of these insects in a logical way in Figure 28. In the 

 first column of this plate is a systematic analysis of the known 

 larval habits. In the second are listed the North American 

 species or genera known to follow any particular habit. And 

 in the third the structure of these larvae, so far as the writer 

 has personally studied them, is indicated. 



