Isidore of Seville [7th century CE] (Etymologies, Book 12, 8:5): The buprestis is a small animal in Italy, similar to the scarab, a long-legged animal. It lies in wait for cows [bos] in particular among the pasturage, whence it takes its name, and if it is eaten it so inflames with the contagion of its poison that the cow bursts. - [Barney, Lewis, et. al. translation]

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Worms 9.43): The stuprestis [buprestis] is a small worm in Italy, as Isidore says, very similar to a scarab, having long legs. It deceives animals by hiding among the grass, but especially the cow [bos], hence its name. As soon as a cow eats the grass where the worm hides and touches its gall, the cow becomes so inflamed and swollen that it immediately bursts in the middle of its entrails. - [Badke translation/paraphrase]

Bartholomaeus Anglicus [13th century CE] (Liber de proprietatibus rerum, Book18.13): Plinius saith, yt there is a little beast like to Ecarabeus, and is called Bupestris, and this Bupestris beguileth and betrayeth the Oxe in the grasse, and that is (as it is sayde) for the Oxe treadeth on him. For this Bupestris lyeth among hearbs and grasse that the Oxe loveth, and hideth him therein: and the Oxe gathereth his meate, and swalloweth this beast Bupestris, & when this beast Bupestris is swallowed, hée chafeth sodeinely the liver of the Oxe, and maketh him break with great paine and sorrow. And the Oxe dyeth with woe and sorrowe that commeth of the venimme of that beast Bupestris, when hée commeth into the Oxe wombe amongst his meate. - [Batman]