The Glow- Worm and Other Beetles 



The cause of this total absence of females is 

 easy to understand. 



If we remove a few clods from the area 

 occupied by the nests, we see that, though all 

 the males have already opened and aban- 

 doned their cells, the females, on the con- 

 trary, are still enclosed in theirs, but on the 

 point of soon taking flight. This appearance 

 of the males almost a month before the emer- 

 gence of the females is not peculiar to the 

 Anthophorae; I have observed it in many 

 other Bees and particularly in the Three- 

 horned Osmia (0. tricornis}, who inhabits 

 the same site as the Hairy-footed Antho- 

 phora (A. pilipes). The males of the Os- 

 mia make their appearance even before 

 those of the Anthophora and at so early a 

 season that the young Sitaris-larvae are per- 

 haps not yet aroused by the instinctive im- 

 pulse which urges them to activity. It is 

 no doubt to their precocious awakening that 

 the males of the Osmia owe their ability to 

 traverse with impunity the corridors in 

 which the young Sitaris-grubs are heaped to- 

 gether, without having the latter fasten to 

 their fleece; at least, I cannot otherwise ex- 

 plain the absence of these larvae from the 

 backs of the male Osmiae, since, when we 

 place them artificially in the presence of these 

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