Whilst I was busied in these observations, a number of cattle came running over the fields with the greatest velocity. Even the most miserably lean cows, which one would think scarcely able to drag one leg after another, went skipping along like does. _Hic pauper cornua sumit_[46]. They twisted their tails round and round, and went bounding and frisking about, till they at length reached a puddle, where they stopped all at once, as having found a sure asylum against the enemy that had put them to flight. Anxious to investigate what it could be that excited such extraordinary agitation, and prompted such exertions as neither the whip nor the fear of immediate death could occasion, I discovered it to be an insect which I had already met with lower down in the country, and which is no other than an _Oestrus_ or Gad-fly, (_Asilus crabroniformis_). Our Natural Historians confound the _Oestrus_ with the _Tabanus_, which are as distinct from each other as a hare from a bear[47]. Cattle indeed are as much incommoded by the _Broms_ (_Tabanus bovinus_) as by the very worst of the Fly or _Musca_ tribe, to which the _Tabanus_ certainly belongs; but by the _Oestrus_ (_Asilus_) they are frightened out of their wits. This insect does not fix itself on the body of the animal, but on the feet, between the larger and smaller hoofs. As it scarcely ever flies higher above the earth than two or three spans, and in general not more than four or five inches, the cattle, when aware of it, run as fast as they can till they get their feet into water or marshy ground, in which situations they are free from danger. The habit of the insect is that of an _Ichneumon_, and it much resembles a Hornet, being of a yellowish colour, with a small sharp point at its tail curved forwards. See the figure and description of Frisch, and my own specimen. [46] "Here the poor takes up horns." Alluding to Horace's "_addis cornua pauperi_." [47] By this comparison, and the subsequent allusion to an _Ichneumon_ and a Hornet, Linnæus at the present period appears to have taken this _Asilus_ for one of the hymenopterous order, and he even calls it an _Ichneumon_ in _Act. Upsal. ann. 1736, p. 29, n. 8_. The history of its attacking the feet of cattle is given in the first edition of _Fauna Suecica_, 308, on the authority of the country people, but is omitted in the second, probably because Linnæus found he had been misinformed. My learned entomological friend the Rev. Mr. Kirby observes that the real _Oestrus Bovis_ is, as has from all antiquity been believed, the cause of the above-described agitation in cattle, who escape it by running into cool damp places, which it dislikes to frequent. _June 18._ Sunday.