394 OBSERVATIONS ON BIRDS. 



eating a deadly disorder to cattle. But the truth of the matter is, 

 the malady above mentioned is occasioned by the dZstrus bovis, a 

 dipterous insect, which lays its eggs along the chines of kine, where 

 the maggots, when hatched, eat their way through the hide of the 

 beast into the flesh, and grow to a very large size. I have just 

 talked with a man who says he has more than once stripped calves 

 who have died of the puckeridge ; that the ail or complaint lay 

 along the chine, where the flesh was much swelled, and filled with 

 purulent matter. Once I myself saw a large rough maggot of this 

 sort squeezed out of the back of a cow. 



These maggots in Essex are called wornils. 



The least observation and attention would convince men that 

 these birds neither injure the goatherd nor the grazier, but are per- 

 fectly harmless, and subsist alone, being night birds, on night 

 insects, such as Scarabcei and Phalcence; and through the month of 

 July mostly on the Scarabccus solstitialis, which in many districts 

 abounds at that season. Those that we have opened, have always 

 had their craws stuffed with large night moths and their eggs, and 

 pieces of chaffers : nor does it anywise appear how they can, weak 

 and unarmed as they seem, inflict any harm upon kine, unless they 

 possess the powers of animal magnetism and can affect them by 

 fluttering over them. 



A fern-owl this evening (August 27) showed off in a very unusual 

 and entertaining manner, by hawking round and round the circum- 

 ference of my great spreading oak for twenty times following, 

 keeping mostly close to the grass, but occasionally glancing up 

 amidst the boughs of the tree. This amusing bird was then in pur- 

 suit of a brood of some particular phalasna belonging to the oak, 

 of which there are several sorts ; and exhibited on the occasion a 

 command of wing superior, I think, to that of the swallow itself. 



When a person approaches the haunt of fern-owls in an evening, 

 they continue flying round the head of the obtruder ; and by 

 striking their wings together above their backs, in the manner that 

 the pigeons called smiters are known to do, make a smart snap ; 

 perhaps at that time they are jealous for their young, and their noise 

 and gesture are intended by way of menace. 



Fern-owls have attachment to oaks, no doubt on account of food ; 

 for the next evening we saw one again several times among the 

 boughs of the same tree ; but it did not skim round its stem over 

 the grass, as on the evening before. In May these birds rind the 

 ScarabcEiis melolontha on the oak, and the Scarabaus solstitialis at 



