The Mason-bees 



take refuge in the old galleries or in the Inter- 

 stices of the stone-heaps in the harmas. 



The same nests are frequented by two 

 Osmia-bees {Osmia tricornis and Osmia 

 Latreillii), who build their cells In the galler- 

 ies left at their disposal by the Chalicodomae. 

 The most numerous is the first, the Three- 

 horned Osmia. It was a splendid opportunity 

 to try and discover to what extent the sense 

 of direction may be regarded as general in. 

 the Bees and Wasps; and I took, advantage 

 of it. Well, the Osmias {Osmia tricornis)^ 

 both male and female, can find their way back 

 to the nest. My experiments were made very 

 quickly, with small numbers and over short 

 distances; but the results agreed so closely 

 with the others that I was convinced. All 

 told, the return to the nest. Including my 

 earlier attempts, was verified in the case of 

 four species: the Chalicodoma of the Sheds, 

 the Chalicodoma of the Walls, the Three- 

 horned Osmia and the Warted Cerceris 

 {Cerceris tiiberciilata) ^ Shall I generalize 

 without reserve and allow all the Hymenop- 

 tera" this faculty of finding their way in un- 



^Insect Life: chap. xix. — Translator's Note. 



*The Hymenoptera are an order of insects having four 



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