i SOCIALES STINGLESS BEES 6 I 



introducing a female Psithyrus to a nest of Bombus in which a 

 Psithyrus was already present as an established guest, the latter 

 asserted its rights and drove away the new comer. Hoffer also 

 tried the experiment of placing a Psithyrus campestris in the nest 

 of Bombus lapidarius a species to which it was a stranger ; not- 

 withstanding its haste to fly away, it was at once attacked by 

 the Bonibus, who pulled it about but did not attempt to sting it. 



When Psithyrus is present in a nest of Bombus it apparently 

 affects the inhabitants only by diminishing their stores of food to 

 so great an extent that the colony remains small instead of largely 

 increasing in numbers. Although Bombus variabilis, when left 

 to itself, increases the number of individuals in a colony to 200 

 or more, Hoffer found in a nest in which Psithyrus was present, 

 that on the 1st of September the assemblage consisted only of a 

 queen Bombus and fifteen workers, together with eighteen speci- 

 mens of the Psithyrus, eight of these being females. 



The nests of Bombus are destroyed by several animals, probably 

 for the sake of the honey contained in the pots ; various kinds 

 of small mammals, such as mice, the weasel, and even the fox, 

 are known to destroy them ; and quite a fauna of Insects may be 

 found in them ; the relations of these to their hosts are very little 

 known, but some undoubtedly destroy the bees' larvae, as in the 

 case of Meloe, Mutilla and Conops. Birds do hot as a rule attack 

 these bees, though the bee-eater, Merops apiaster, has been known 

 to feed on them very heavily. 



The genera of social bees known as Melipona, Trigona or Tetra- 

 gona, may, according to recent authorities, be all included in one 

 genus, Melipona. Some of these Insects are amongst the smallest 

 of bees, so that one, or more, species go by the name of " Mosquito- 

 bees." The species appear to be numerous, and occur in most of the 

 tropical parts of the continents of the world, but unfortunately 

 very little is known as to their life-histories or economics ; they 

 are said to form communities consisting at times of a countless 

 number of individuals ; but it has not been thoroughly ascer- 

 tained whether these are the produce of a single queen, as in 

 the case of the hive-bee, or whether there may be more than one 

 egg-producer in each community. The late F. Smith thought 

 the former of these alternatives would prove to be correct. 

 These mosquito-bees are frequently spoken of as stingless bees, 

 but this is not quite correct, for although they do not sting, 



