THE CANADIAN ENTOMOLOGIST 161 



5. fidvipes fulvipes Macquart differs from the subspecies just 

 described in the following characters; sides of frontal vitta parallel 

 or slightly converging backward (should probably be same varia- 

 tion in dissidia); second antennal segment dull orange; palpi light 

 (dull orange) ; hairs covering anterior spiracle mostly grayish, 

 bases dark; those of anterior margin of posterior spiracle dark at 

 base only; those of spiracular cover yellowish, perhaps faintly 

 darkened basally; epaulets dull orange, brownish basally (Ravinia- 

 like) ; coxae, trochanters, femora and tibiae of all legs dull orange, 

 tarsi brown or brownish orange; anterior dorsocentrals not dif- 

 ferentiated except that one or two show anteriorly; anterior 

 postsutural dorsocentrals not differentiated; two or three sterno- 

 pleurals, middle one weak if three are present; first genital seg- 

 ment with or without marginal bristles, if present very slender 

 and hair-like, several each side of centre; forceps only darkened 

 distally. 



The most striking of the differences above noted is the dull 

 orange colour of the second antennal segments, palpi, epaulets 

 and first four segments of the legs. Though all the anterior 

 dorsocentrals are differentiated in the subspecies dissidia, this may 

 be a variable character;' the absence of marginal bristles on the 

 first genital segment may perhaps be variable. In the smaller 

 of the two specimens of fulvipes the bearded character of the middle 

 tibiae is far less distinct, the anterior tibia lacks a beard-like line 

 of short hairs distally, the posterior beard of the hind tibia is much 

 stronger than the anterior, and the veritral surface of the anterior 

 coxa has an irregular row of bristles at each side only. 



AN INTERESTING CASE OF INSTINCT. 



BY L. M. STOHR, ST. ALEXANDER'S COLLEGE, IRONSIDE, QUE. 



While collecting last fall branches of Sumach which, on ac- 

 count of their great medullar development, often shelter different 

 kinds of aculeate Hymenoptera, I was fortunate enough to find 

 one that furnishes a striking example of instinct. The stalk re- 

 ferred to had been used as a dwelling by several Hymenoptera, 

 as might be seen from the old cells, whose location is still perfectly 

 noticeable. Later on a woodpecker, having remarked t1ie presence 



May, 1917 



