112 APID.E. 



differences are common among all parasitic insects as a rule. This 

 arises, no doubt, from the amount of food consumed by the larva. It 

 is not an uncommon circumstance to find two Nomadoe in a single cell 

 of the bee upon which it is parasitic ; in such cases one or both are 

 usually small examples. Yar. /3 of Kirby is by no means common. 

 The larger the specimens the lighter is the general coloration ; the 

 smaller and darker specimens have the metathorax entirely black, 

 the red markings on that part of the thorax being very inconstant; 

 in the males it is always black : this sex has sometimes two red 

 spots on the scutellum ; but they are frequently obsolete ; small males 

 have the scape occasionally quite black, or with only a minute yellow 

 spot in front. This species is parasitic on several species of Andrena, 

 frequently so on A. trimmerana, A. atriceps, A. fulva, and A. 

 nigro-cenea. 



2. Nomada borealis. 



N. atra, clypei margine rufo, thorace toto nigro ; abdominis seg- 

 mento secundo macula marginali triangulari flava, reliquis luteo 

 fasciatis. 



Nomada borealis, Zett. Ins. Lapp. 470 2 . 



Nyland, Notts, ur Stilish, pro Faun, et Flo. Fenn. i. 181. 



Smith, Bees Great Brit. 123 S $ • 



Schenck, Xass. Bien. 185. 



Thorns. Hym. Scand. ii. 192. 

 Nomada inquilina, Smith, Zool. ii. 60o. 



Female. Length 4-5 lines. — Head and thorax black ; the margin 

 of the clypeus, the labrum, mandibles, and a spot at the vertex of 

 the eyes ferruginous ; the flagellum beneath, the apex of the joints 

 above, and the extreme base and apex of the scape beneath ferru- 

 ginous, the third joint sometimes entirely so ; the labrum has a 

 minute tooth in the middle. Thorax : the tegulae, tubercles, and 

 two spots on the scutellum, frequently united, are ferruginous ; the 

 coxa? and femora black, their extreme apex ferruginous ; the tibiae 

 and tarsi ferruginous, the anterior tibia? having a black spot behind. 

 Abdomen ferruginous, the base black ; the second segment has a 

 large ovate macula, pointed within, the third a smaller spot, or 

 sometimes a narrow transverse line, the fourth a broader fascia 

 with a minute spot beyond its termination laterally, and the fifth a 

 quadrate macula, yellow ; the basal segment has usually a minute 

 black dot on each side, its apical margin, as well as those of the 

 three following segments, nigro-piceous. B.M. 



Yar. j3. The femora more or less ferruginous in front and at their 

 apex. 



Male. Length 4 lines. — Head and thorax black, the anterior mar- 

 gin of the clypeus narrowly yellow : the labrum and mandibles 

 yellow, the latter ferruginous at their tips ; the face thinly covered 

 with silvery white pubescence ; the antennae black, the flagellum 

 rufo-testaceous beneath. Thorax thinly covered with griseous pu- 



