542 NATURAL HISTORY OF ARTHROPODS. 



constructed, the peculiar manner in which the cells are made accounting for the 

 irregularity in their arrangement. The nest rapidly increases in size, as the queen 

 remains fertile throughout the summer. In the construction of their nests, the bees 



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adapt themselves to circumstances in an interesting way, and avail themselves of such 

 materials as are most readily found. Where moss is abundant, the nests are entirely 

 constructed of this material, and Smith mentions an instance in which a female, found- 

 ing a colony in the grass near a stable, collected a quantity of the bundles of horse-hair 

 accumulated from the currying of horses, and composed her nest entirely of this sub- 

 stance. Another instance is mentioned where a female of Bombus pratorum took 

 possession of the nest of a robin, built high up on a porch. 



About the middle of the summer, eggs are deposited, from which hatch small females 

 and males. The small females are supposed to be able to lay only male eggs. Accord- 

 ing to Putnam, all eggs laid by the queen after the last of July produce only the 

 large females or queens, which, after impregnation by the males, seek suitable places 

 for hibernation, while the other inhabitants of the nest die on the approach of cold 

 weather. 



The species of this genus are subject to the attacks of several parasites. Besides 

 the species of the genus Aputkus, which we shall consider next, many nests swarm with 

 a species of Acarus which devours the wax and honey. The larva? of Tinea pellionella 

 abound in many nests. The two beetles Atitfierophagus glaber and A. ochraceus feed 

 upon the stored-up food, and Anobiimi paniceum is said to have the same habit. 

 Meloe and Stylops also infest Dombus, and species of the dipterous genera, Volucellct, 

 Conops, Anthrax, and Anthorni/in arc also found in the nests. 



The numbers of which the colonies of bumble bees consist vary greatly with the 



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different species. A nest of -Bonibus fragrans, examined by Smith at the end of 

 August, contained only five females and twenty workers, while a nest of B. terrestris, 

 examined at the same time, contained thirty-five females, twenty males, and one hun- 

 dred and sixty workers, a total of two hundred and fifteen, and at this time a majority 

 of the males and females were supposed to have left the nest. 



The genus Apathus closely resembles Bombus. Nine North American species have 

 been described. The economy of this genus is not well understood. Its species live 

 in the nests of Hombus, the species of which they mimic in appearance, but what office 

 they perform is not well known. A parasitic connection is conjectured, but not proven. 

 They seem to be on the most friendly terms with their hosts. Smith says : " It has 

 been supposed, from the very close resemblance of the Apathi to the Bombi, that the 

 former are an idle race, reared at the expense of the industrious bees, and Avearing a 

 livery in imitation of them for the purpose of deception ; but there can be little doubt 

 of these aristocrats of the community performing important and necessary duties 

 highly conducive to the general prosperity of the whole." 



"With the genus Apis the characters are as follows: Males. Eyes very large, 

 occupying one-fifth of the head, meeting on the vertex ; posterior tibias slender at base, 

 gradually widening towards apex. Females and Workers. Eyes lateral, elongate, 

 not meeting on the vertex. Wings having one marginal and three sub-marginal cells ; 

 labial palpi four-jointed; maxillary palpi one-jointed. Eyes pubescent; posterior 

 tibiae not spined ; basal joint of posterior tarsi of workers concave, transversely 

 ridged, each ridge having a thick-set fringe of stiff hairs. Male and female with 

 simple tarsi. 



The habits of the common honey bee (Apis mellifica) have been studied for many 



