An additional argument against the explanation [that the "kinim" mentioned by Chazal are a different otherwise unknown species which does in fact reproduce spontaneously] is that throughout the ages, the commentaries on the Talmud and halachah spoke of the permissibility of killing lice on Shabbos due to their spontaneous generation. The recent authorities, such as the Chafetz Chaim, where writing in living memory; they were certainly speaking of the same lice with which we are familiar. (Mysterious Creatures page 198-199)Although R. Slifkn suggest we essentially have a living "mesorah" about the identity of "kinim" it seems that it may not be that simple. The Chafetz Chaim (M.B. 316:35) gives a discription of a "parosh", implying there was some ambiguity which needed clarification. Indeed the translation by Feldheim Publishers on this Mishneh Berurah includes a footnote which says:
One is a flea (parosh) and the other is a louse (kinah), but there is a dispute among the Poskim as to which is which. (page 241)It would seem that there is some controversy about the identity of this species. While I am not inclined to suggest this provides a great solution to the challenge we are presented with I think it is worthwhile that this argument is not as sound as it would seem.