7. OSMIA. 151 



when discovered in 1849 one third of the cocoons were found to bo 

 empty; in 1850 a few males and females appeared; in 1851 the 

 same occurrence took place, and then the stone was presented to 

 the British Museum and placed in my hand for observation ; in 

 April 1852 all the rest of the cocoons produced bees or parasites, 

 the latter proving to be a species of ruby-tailed fly, Chrysis tricolor, 

 a species new to the British list. In the first instance all the de- 

 posit was subjected to the same influences and had produced larvae ; 

 the same may be said of them when taken by Mr. Robertson to 

 Edinburgh, and yet only a few of each sex were developed. The fol- 

 lowing year produced the same result ; and the third year the rest 

 appeared. What was the cause of this retarded development it is 

 difficult to conceive. 



Osmia xanihomelana belongs to the division of mason-bees ; its 

 nest is usually constructed at the roots of grass, but occasionally 

 in a hollow chamber about an inch underground. The cells are 

 pitcher-shaped, and constructed of mud mixed with small pebbles; 

 outside they are very rough, but the inner surface is perfectly 

 smooth, the whole reminding one of the texture of a swallow's nest. 

 The cells are each about 5 lines in length, rounded at the bottom, 

 but flattened at the top and closed by a lid, which the bee con- 

 structs after having provisioned the cell ; the cells are placed close 

 side by side and are more or less joined together ; a nest when com- 

 pleted usually contains five or six cells. This species appears in May 

 or the beginning of Juno ; its brood undergoes its transformations and 

 attains the perfect condition by the end of August or the beginning 

 of the following month ; in this state it passes the winter months ; 

 but occasionally a few remain through the winter in the larval con- 

 dition. 



There are several parasites on the different species of Osmia be- 

 sides the bee parasites of the genus Stelis : Chrysis ignita is a com- 

 mon destroyer of the larvae of 0. rufa, and C. fulgia has been bred 

 from the cocoons of the same bee ; but its most destructive parasite 

 is a chalcididous insect, Monodontomerus dentipes ; large numbers of 

 this insect have been obtained from their nests. Chrysis ignita has 

 been reared from the cocoons of Osmia xanihomelana ; and it would 

 no doubt attack the nest of any species of bee that it found adapted 

 to its purpose ; bee or wasp suits it equally well. I have obtained 

 it in plenty from a nest of Vespa rufa, also from nests of Odgnerus 

 antilope ; their larva) appear to be almost omnivorous. 



Osmia papaveris (the Anthocopa of St.-Fargeau) is not included 

 in this genus, there not being any reliable evidence of its having been 

 found in this country. Shuckard has included 0. papaveris in his 

 work ' British Bees,' on the authority of specimens placed in the 

 collection of British Aculeata in the British Museum. There are 

 three specimens of the female, and two males of Osmia adunca 

 arranged with them as being those of 0. papaveris : these are all 

 without locality ; but they have small tickets bearing numbers that 

 exactly correspond with others attached to species never found in 

 this country. There can be little doubt of the specimens of the 



