Hypoderma. 87 



Wings with the first posterior cell open, ending before apex of wing; 

 angle on discai vein obtuse; posterior cross-vein placed just on the 

 angle and tims in continuation of apical cross-vein and both parallel 

 with the wing margin; anal vein reaching to the margin; cubital 

 vein without bristles at base. Wing-membrane corrugate. Thoracai 

 squamula large, not fringed. 



The fullgrown larva is rather broad, elongated oval, flattened 

 above, arched below; the segments have transversally arranged 

 spinules, most numerous on the ventral side; the larva has no mouth 

 hooks in its last stages. The species are parasitic on cattle and on 

 Cervus elaphus and capreolus (one is doubtfully recorded from the 

 ass and some, only known as larvæ, from Capra^ Mosehus and anti- 

 lopes). Our species live on cattle. The eggs are deposited on the hairs, 

 the young larva then bores in, and it seems to migrate more or less 

 in the body, but towards the stage before the last it goes to the 

 skin, and here are then formed swellings, the so-called warbles, in 

 which the larva lies with the posterior end outwards towards the 

 opening found in the warble. When fullgrown it leaves the warble 

 through the opening, falls to ground, where it pupates. H. bovis 

 deposites the eggs in summer, generally in July; the warbles begin 

 to appear in February, and the larva is fullgrown and leaves the 

 warble in May and June; the pupa rests about a month, so that 

 the imago appears at the end of June and in July. In earlier time it 

 was commonly accepted that the young larva, as said, bores in 

 through the dermis, but as the larvæ were often found in the host, 

 migrating far from the surface, the opinion was advanced that 

 the host got the larva in by licking, and that the larva then later 

 on went to the skin. New investigations, especially by Stub in our 

 country, by Bergman on Oedemagena tarandi (Entom. Tidskr. 38, 

 1917) and by American investigators (see Hadwen, Depart. of Agric. 

 Canada. Se. Ser. 27, 1919 and Bishopp, Laake, Brundrett and Wells, 

 U. S. Dep. of Agric. Dep. Bull. No. 1369, 1926.) have, however, now 

 brought it beyond doubt that the young larva bores in through the 

 skin. — When H. bovis deposits its eggs, its presence has a very 

 peculiar influence on the cattle and gives rise to the well known 

 behaviour of this, known as the stampede, the cattle then galloping 

 furiously with the tail stretched out or upwards and if possible 

 seeking into water. It is rather surprising that the fly, which in no 

 way directly hurts the cattle, should cause this strong effect, and 

 there was therefore spoken of instinct; after Bergman's investigations 



