17. APATHTJS. 219 



This species is common in many localities, and usually all the 

 varieties occur at the same spot ; I have taken the black male in 

 coitu with the yellow-banded female. This is one of the most protean 

 species of the genus, and a familiar acquaintance with these insects 

 is necessary to enable any one to separate all the sexes from the 

 closely allied species. I have seen St.-Fargeau's typical specimen 

 of his B. soroensis ; and it is certainly a female of B. subtermneus. 



Genus 17. APATHUS. 



Apis (pt), Fair. Ent. Syst. ii. 317 (1793). 

 Bombus (pt.), Fair. Syst. Piez. 342 (1804). 

 Breinus (pt), Jurine, Hym. 257 (1807). 

 Apathus, Newm. Ent. Mag. ii. 404 (1834). 

 Psitkyrus, St.-Farg. Hym. ii. 424, nee Hiibner (1841). 



The generic characters are those of the genus Bombus, with the 

 following distinguishing differences. The posterior tibiae exteriorly 

 convex, pilose, and not furnished with a corbicula for conveying 

 pollen, only slightly widened towards the apex ; the basal joint of 

 the posterior tarsi not toothed at its base above ; the abdomen 

 incurved more or less at the apex, convex, and subglabrous ; the 

 apical ventral segment with its lateral margins elevated. The pos- 

 terior tibisa of the male very convex, and only slightly attenuated at 

 the base. 



The geographical distribution of the Apatlii is presumably co- 

 extensive with the Bombi ; if this is the case, much remains to be 

 discovered, since, at the present time, no species has been brought 

 from India or China, although several species of Bombus are 

 known to inhabit those countries. A single species has been 

 found in Brazil, two or three in Mexico, two in British Columbia, 

 one in Vancouver's Island, and seven in North America ; in Europe 

 we are acquainted with five species, four of which are found in this 

 country. 



St.-Fargeau established this genus under the name of Psitliyrus, 

 a name preoccupied in Lepidoptera; Newman's name Apathus 

 (signifying want of affection, from the circumstance of their leaving 

 their offspring to be nurtured by the industrious Bombi) is exceed- 

 ingly appropriate ; it has the priority and is consequently adopted. 



The species found in this country do not confine their parasitism 

 to one species of Bombus ; or, if there is an exception to this, it is in 

 the case of the Apathus rupestris, which hitherto has, I believe, only 

 been observed in the nest of Bombus lapidarius. A. campestris has 

 been found in the nest of B. hortorum and B. latreillellus ; A. bar- 

 butellus frequents the nests of B. pratorum and of B. jonellus ; 

 A. vestalis those of B. virginalis and of B. lucorum. 



These bees are the only parasitic ones that greatly resemble their 

 hosts; and this close resemblance is probably requisite to enable 

 them to enter the nests of the Bombi without molestation. The 

 structure of these bees marks them out as the aristocracy of the 



