A healthy adult mite is up to 75% water and must retain this water balance to breed. House dust mites can produce up to 20 droppings a day, each dropping can containing 14 fully identified potential allergens, many of which are enzymes. House dust mites are a major cause of allergy worldwide.
Medical Entomology for Students By Mike Service Published by Cambridge University Press, 2008 ISBN 0521709288, 9780521709286
'Allergens and their role in the allergic immune response', TAE Platts-Mills, JA Woodfolk, "Immunological Reviews' 2011, Vol.242: p 51-68