. The Acarina or mites. A review of the group for the use of economic entomologists. Mites. THE ACAEIXA OR MITES. 13 rebuilt from the disintegrated tissues of the preceding stage. The genital organs are, however, not affected by these histolytic processes. Renter has recently (1909) tabulated the known life histories of mites, showing that most species have three nymphal stages. In several cases the second stage is absent or has not been observed; in most of the sarcoptid mites there are but two nymphal stages, while in the Eriophyidae and Ixodidae there is but one nymphal stage. Various autho
. The Acarina or mites. A review of the group for the use of economic entomologists. Mites. THE ACAEIXA OR MITES. 13 rebuilt from the disintegrated tissues of the preceding stage. The genital organs are, however, not affected by these histolytic processes. Renter has recently (1909) tabulated the known life histories of mites, showing that most species have three nymphal stages. In several cases the second stage is absent or has not been observed; in most of the sarcoptid mites there are but two nymphal stages, while in the Eriophyidae and Ixodidae there is but one nymphal stage. Various authors have expressed their belief in parthenogenesis in Acari, but without experimentation. Miss Foa and Dr. Oudemans have examined most of the alleged cases and show that there is no direct evidence, or that there has been a mixture of species, as in Trouessart's theory of the parthenogenesis of Syringohia. It was also held that Syringophilus was a par- thenogenetic form of Cheyletus norneri; Dr. Oudemans has shown that this is erroneous, and Norner described the males of Syringophi- lus. The cases given by Berlese in the Parasitidae were examined by ^liss Foa, who concluded that there was no proof, for at the proper season the male of each spe- cies appeared, although in some species they live but a brief time. There is, therefore, no positive proof of parthenogenesis in acarians un- less recent claims for parthenogene- sis in a tick should prove to be true. The common impression that most mites are parasitic is entirely erroneous. About half of the known species are not parasitic in any stage, and many which are found attached to insects and other animals are not true parasites thereon. The relation between the host and the parasitic acarian is of such a varied nature that several writers have made elaborate classifications of their relationships. But, as with most classifications, there are intermediate forms. It is evident that the parasitic habit has originated independently
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