Mites have been known in Egypt since the beginning of the 19th century, while ticks were known since the time of Ancient Egyptians as early as 1550 B.C. The small size of mites is responsible for the lack of information available on them. Thus, specimens must be mounted on microscopic slides and studied under magnifications as a high as one thousand diameters. Furthermore, the techniques are not the same as those used in various Zoological sciences, although many special methods are borrowed from both Zoology and Entomology. The Acari is not small enough to be handled like protozoans or soft bodied enough to be treated as worms and they are too small to be studied like insects. The present study is going to focus on: 1. Survey of soil mite taxa in two soil types (sandy and clayey soils) under the same crop rotation. 2. Study of population density of soil mites in both soil types under the same crop rotation. 3. Study of population density of soil mites under different crops in sandy soil. 4. Biological and morphological studies on the soil astigmatid mite Histiogaster bacchus which is firstly recorded in Egypt. 5. Demography of Histiogaster bacchus.