In South Bohemia a case was discovered of a yearling colt attacked by the larva of the IIIrd instar of the deer warble fly Hypoderma diana Brauer. The dead, almost mature larva of the fly was squeezed out of a subcutaneous lump above the shoulder in the first decade of April, 1985. The case is evaluated from the point of view of the possibility of the transition of specific parasites--warble flies--to another host. The attacking of a non-specific kind can occasionally occur only when there is a large number of the parasites and both kinds of host. At present the degree of attacking of deer by subcutaneous warble flies is high and therefore under favourable circumstances even domestic animals can be attacked by this type of warble fly. The above case is the first to be ascertained of a horse being attacked by a deer warble fly.

A 4-years monitoring of Hypoderma diana in horses from the Czech Republic