156 THE NATURAL HISTORY 



of side-fly, from its running sideways like a crab. It 

 creeps under the tails, and about the groins of horses, 

 which, at their first coming out of the north, are rendered 

 half frantic by the tickling sensation ; while our own 

 breed little regards them. 



The curious Reaumur discovered the large eggs, or 

 rather pupse, of these flies as big as the flies themselves, 

 "which he hatched in his own bosom. Any person that 

 will take the trouble to examine the old nests of either 

 species of swallows may find in them the black shining 

 cases of the pupie of these insects : but for other par- 

 ticulars, too long for this place, we refer the reader to 

 L'Histoire d'lnsedes of that admirable entomologist. 

 Tom. iv. pi. 11. 



LETTER XVI 



Selbohne, Nov. 20, 1773. 

 Dear Sir, 



In obedience to your injunctions I sit down to give you 

 ^ome account of the house-martin, or martlet ; and, if 

 my monography of this little domestic and familiar bird 

 should happen to meet with your approbation, I may 

 probably soon extend my inquiries to the rest of the 

 British hirundines — the swallow, the swift, and the bank- 

 martin. 



A few house martins begin to appear about the six- 

 teenth of April ; usually some few days later than the 

 iiwallow. For some time after they appear the hirundines 

 in general pay no attention to the business of nidification, 

 but play and sport about either to recruit from the fatigue 

 of their journey, if they do migrate at all, or else that 

 their blood may recover its true tone and texture after 



