Bristowe, writing in the book British Spiders, 1951, said of this time in F. O. Pickard-Cambridge's life: "Whilst he was still in his 30s, however, a marked change came over him which led to misfortune".

This unfortunate new tendency also spilled over into his natural history work, and he had fierce arguments with other scientists, such as Karsch, over questions of nomenclature.

The extreme political and moral ideas which he felt it his duty to preach somewhat indiscriminately in the later years of his life ultimately brought about a partial severance between him and my father [O. Pickard-Cambridge], but his early death was undoubtedly a loss to science as well as to those who had delighted in his companionship.

He goes on to quote The Times from 1905 (no date given) which reported that no cause other than mental strain could be assigned for the act, and that a verdict of "Suicide while temporarily insane" was returned at the inquest.

(In Bristowe's own book The World of Spiders[5] he writes erroneously that F. O. Pickard-Cambridge's papers were published "between 1889 and 1905 (three years after his untimely death)".)