1446 Insects. 



established in such situations. I have had no opportunity of tracing 

 the economy of the species, but there is an interesting account of its 

 habits in the first volume of the e Entomological Magazine.'* It is 

 there detailed in substance as follows ; the female having fixed upon 

 a post or other object suited to 4ier purpose, she first perforates to the 

 depth of an inch or more in a horizontal direction, then, changing her 

 course, she works in a perpendicular one until she has constructed a 

 tube twelve or fourteen inches in length ; she then changes the direc- 

 tion of the tube to the horizontal, and continues it to the outside of 

 the post ; she then forms her first cell at the bottom of the tube, and 

 having stored it with pollen and honey she deposits an egg and clo- 

 ses it up ; a succession of these cells is constructed to the number of 

 a dozen or more, when having finished her task, she closes up both 

 ends of the tube, the lower one with fine particles of agglutinated sand, 

 but the top she secures by the addition of some small pebbles, &c. 

 for greater security ; when the bees are fully developed, they are said 

 to make their escape from the lower end of the tube, those eggs which 

 were deposited first being necessarily the first to arrive at maturity. 

 This is in exact accordance with the history of Xylocopa violacea, as 

 detailed by Reaumur. These histories are remarkable, inasmuch as 

 they are directly opposed to my own observations on every species of 

 bee which I have had an opportunity of observing. I have invariably 

 found that about half of the number of eggs, those first deposited, pro- 

 duced females, the rest in the upper cells being males, and these al- 

 ways come forth a few days before the females : — this is the history of 

 Megachile Willughbiella, of Osmia leucomelana, O. bicornis, O. bi- 

 color, and O. tunensis, and also of Sarapoda bimaculata ; the same 

 will apply to several of the fossorial Hymenoptera, as Crabro cephalo- 

 tes, C. dimidiatus, C. Xylurgus, and Rhopalum rufiventris. I cannot 

 but suspect that there is some mistake in the details quoted, and a 

 circumstance which I observed some years ago, tends to confirm me 

 in my suspicion ; being at that time on an entomological excursion 

 in Hampshire, my attention was attracted to some bees which I ob- 

 served entering the straws of the thatch of a barn ; these proved on 

 capture to be Chelostoma ; I did not find more than five or six cells 

 in one straw, in some of which was a small larva feeding, the cell 

 first formed being close to the first knot in the straw ; in this instance 

 I cannot conceive but that the first bee that would emerge must be 

 from the cell nearest to the entrance of the tube, the cell last stored ; 



* Ent. Mag. i. 



