The most important House dust mites are Dermatophagoides pteronyssinus and D. farinae. In subtropical and tropical regions the Storage mite Blomia tropicalis is also a major source of allergens, co-existing with D. pteronyssinus.
D. pteronyssinus, though it has a worldwide distribution, seems to be more abundant in Europe than in America. It prefers more humid climates than D. farinae does.
Allergon cultivates these mites with a purity of at least 95% and the remaining part consisting of cultivation media.