One of the most famous is the Chrysomelid beetle, _Diamphidia simplex_, the body fluids of whose larvæ are used by certain South African bushmen as an arrow poison. Its action is due to the presence of a toxalbumin which exerts a hæmolytic action on the blood, and produces inflammation of the subcutaneous connective tissue and mucous membranes. Death results from general paralysis. Krause (1907) has surmised that the active principle may be a bacterial toxin arising from decomposition of the tissues of the larva, but he presents no support of this view and it is opposed by all the available evidence. In China, a bug, _Heuchis sanguinea_, belonging to the family Cicadidæ, is used like the Meloidæ, to produce blistering, and often causes poisoning. It has been assumed that its vescicating properties are due to cantharidin, but the presence of this substance has not been demonstrated. Certain Aphididæ contain a strongly irritating substance which produces, not merely on mucous membranes but on outer skin, a characteristic inflammation. It has been frequently reported that the larvæ of the European cabbage butterfly, _Pieris brassicæ_, accidentally eaten by cows, horses, ducks, and other domestic animals, cause severe colic, attempts to vomit, paralysis of the hind legs, salivation, and stomatitis. On _postmortem_ there are to be found hæmorrhagic gastro-enteritis, splenitis, and nephritis. Kobert has recently investigated the subject and has found a poisonous substance in the blood of not only the larvæ but also the pupæ. FOOTNOTES: [A] This is diametrically opposed to the findings of Bordas (1905) in the case of the European _Latrodectus 13-guttatus_, whose glands are "much larger than those of other spiders." From a considerable comparative study, we should also unhesitatingly make this statement regarding the glands of our American species, _L. mactans_. [B] Dr. E. H. Coleman (Kellogg, 1915) has demonstrated its virulence by a series of experiments comparable with those of Kobert. [C] According to Stiles, the species occurring in the Northwest which is commonly identified as _D. venustus_ should be called _D. andersoni_ (see footnote, chapter 12). [D] It should be remembered that in all the higher Hymenoptera the first abdominal segment is fused with the thorax and that what is apparently the sixth segment is, in reality, the seventh. CHAPTER III PARASITIC ARTHROPODA AFFECTING MAN