264 MAINE AGRICULTURAL EXPERIMENT STATION. 1916. 



60. Wheeler, W. M. Studies on Myrmecophiles III, Microdon. Journ. 



N. Y. Ent. Soc. Vol. XVI, 4, pp. 202, 213, 1908. 



61. Wiedemann, C. R. W. Aussereuropaische Zweiflugelige Insekten 



II, 129, 22, 1830. 



62. Williston, Samuel W. Synopsis N. A. Syrphidae, Bui. U. S. 



Natl. Mus., No. 31. Wash., 1886. 



63. Williston, Samuel W. Copestylum marginatum and Volucella 



fasciata reared from Cactus, Ent. News II, 161, Oct., 1891. 



64. Was mann, E. Vergleichende Studien iiber Ameisen-und Termi- 



tengaste. Haag. Sep, aus Tijdschr. v. Entom. XXXIII, pp. 27-96, 

 pi. I, 1890. 



65. Wasmann, E. Kritisches Verzeichniss der myrmekophilen und 



termitophilen Arthropoden, Berlin, Felix Dames, pp vii-)-23i, 

 1894. 

 Reference to the following important paper on the habits of the 

 genus Chilosia was inadvertently omitted from the table in Figure 

 28, page 207. 



66. Burke, H. E. Black Check in Western Hemlock, U. S. Dept. Agr., 



Bur. Entomology, Circular 61. Discusses habits and life-history 

 of C. alaskensis Hunter and C. hoodianus Bigot and describes 

 their injury to Western Hemlock and Lowland Fir, respectively. 



FIGURES AND EXPLANATIONS 

 EXPLANATION OF FIGURE 29. 



Pipisa pisticoides Willist. 



Side view of larva xi2; A, lateral mouth-hook, immediately in front 



of which is the antenna ; B, anterior larval spiracle ; C, posterior 



respiratory process. 



End view of posterior respiratory process X185 ; showing the two 



stigmal plates, each with a circular plate, interspiracular hairs and 



slk-like spiracles. 



Side view of puparium xi2. 



Dorsal view of adult female xi8. 



Didea fasciata Macq. var. fuscipes Loew. 

 Sculpturing on egg-shell of Didea fasciata fuscipes (q. v.) 



