A number of predacious mites of the PHYTOSEIINAE (family LAELAPTIDAE), found in south-eastern England, mostly in association with fruit trees, are listed. Certain measurements and other characters that are of value in separating species are given. The species found were: Typhlodromus tiliae Oudm., T. cucumeris Oudm., T. tiliarum Oudm., T. rhenanus (Oudm.), T. finlandicus (Oudm.), T. umbraticus Chant, T. massei Nesbitt, T. vitis Oudm., T. soleiger (Ribaga), Phytoseius macropilis (Banks) and two Amblyseius spp. Of these, T. tiliae, T. finlandicus and P. macropilis are normally abundant on apple trees, but only T. tiliae remains abundant on commercially-grown apple trees. For each species a list of plants on which it has been found is given.Details of the life-history of laboratory-reared mites are given and these, together with counts of field populations, show that three generations a year is normal.Predacious phytoseiine mites feed on several species of TETRANYCHIDAE, including Metatetranychus ulmi (Koch) and Tetranychus telarius (L.); when M. ulmi is supplied in adequate numbers, adults of T. tiliae consume 3 mites per day, the nymphs 2 mites per day, on an average. It is thought that they also feed on plant tissue, since individuals survived in the laboratory for a considerable length of time in the absence of phytophagous mites, though eggs were not laid.
Three generations under low versus high neighborhood density affect the life history of a clonal plant through differential selection and genetic drift
