400 Mr, H. St. J. Donisthorpe on the Origin 



nest as soon as the bird begins to build, about the middle 

 of April, and when the full clutch of eggs is laid, about 

 three weeks later, as many as thirty or more specimens 

 may often be found in a single nest. It is, in fact, quite a 

 common species, as I have only once failed to find it in 

 the nest of a tit, a bird familiar enough in any wooded 

 district. I have not succeeded in finding the beetles 

 pairing, but no doubt the eggs are laid soon after the nest 

 is entered, for when it is examined immediately after the 

 young have flown a large number of fully grown larvae 

 may be shaken out of it ; this would be about a month 

 after the last bird's egg is laid. Shortly after this the 

 larvae congregate into a suitable spot (under the lid of a 

 nesting-box in one case, and at the very bottom of a nest 

 in another), and there spin small whitish cocoons packed 

 together in the same plane. The insect remains in the 

 pupal stage for about sixteen days, and then, when pro- 

 perly mature, eats its way out of its cocoon and 

 immediately leaves the nest. It is hard to guess what is 

 the history of the imago after this. Certainly it is found 

 not very rarely on carrion, etc., and there may be a second 

 brood produced in such situations ; but I am inclined to 

 think that this is not the case, but that the beetles 

 hibernate till the following spring." I have thought it 

 best to quote word for word what Dr. Joy has written 

 about this and the next species, and then discuss its 

 relation to our subject. 



Microglossa gentilis, Mark. 



" Found by Mr. F. Smith, at Hampstead, in company 

 with Formica f'ldiginosa " (Janson, Ent. Ann., 1860, p. 101). 



Crotch recorded it in nests of the same ant at Cam- 

 bridge and Weston-super-Mare (Zool, 1862, p. 8139), 

 E. C. Rye mentions that it was taken commonly by Power 

 at Birdbrook, and by Brewer and Power at Mickleham, 

 always with Formica fuliginosa (Ent. Ann., 1866, p. 49). 



Fowler (/. c. p. 25) writes — " In the runs of Formica 

 fuliginosa ; rare, but probably often overlooked, as it 

 doubles itself up and will lie for a quarter of an hour 

 without stirring ; . . . Dr. Power has taken it in consider- 

 able numbers by carefully blowing away the sand, and 

 watching the ant-runs." B. G. Rye found it in numbers 

 in a nest of Lasius fidiginosus at Brent Knoll in Somerset 

 in 1897. I have taken it in some numbers in a nest of 



