NO. 7 PROTECTIVE ADAPTATIONS McATEK 83 



in more detail as showing how the activities of such foes supplement 

 the predatory activities of birds. Take for example the wood-boring 

 beetles, which although they are eaten by birds to an extent that 

 indicates that no special protective adaptation operates in their favor, 

 yet are shielded from most birds during the greater part of their lives 

 by living under bark or even within solid wood. However this habit 

 does not put them out of the reach of predatory and parasitic insects. 

 Thus Kleine records 159 hymenopterous parasites of Cerambycidae. 

 and 136 beetle predators and 157 hymenopterous parasites of Sco- 

 lytidae in Europe. (Ent. Bl. Nurnberg, vols. 4-5, 1908-1909.) The 

 cotton-boll weevil (Authonoiiiits grandls) again passes the larval and 

 pupal stages apparently well hidden from most enemies, yet some of 

 the 66 kinds of birds known to prey upon it remove the immature 

 stages from the cotton bolls, and in addition the weevil has 54 insect 

 enemies, about half of which attack the concealed stages. (Bull. 100. 

 U. S. Bur. Ent. 1912.) 



So it is with the mechanically protected species ; all have in the 

 chains of their life histories weak links, of which hungry predators 

 and assiduous parasites are not slow to take advantage. For contrast, 

 consider the case of the Colorado potato beetle, an insect exposed 

 almost throughout its life history, and with all of the attributes — 

 color, reflex bleeding, nastiness, even poisonous qualities- — of a most 

 highly " protected " insect. Besides the 27 species of wild birds 

 known to feed upon this insect, ducks, chickens, guinea fowls, skunks, 

 snakes, frogs, toads, at least eight species of Pentatomidae, two of 

 Reduviidae among bugs, and eight of Coccinellidae and seven of 

 Carabidae among beetles, l)esides robber flies, wasps, spiders, pha- 

 langids, and mites prey upon the various stages. Despite all of its 

 protective adaptations, the Colorado potato beetle undoubtedly has its 

 full quota of foes ; its rapid increase and spread over the United 

 States was due to enormous increase by cultivation of a favored food 

 plant and not to lack of enemies. Dr. F. H. Chittenden remarks : 

 " Few, if any, noxious insects have so many recorded natural enemies 

 as the Colorado potato beetle." (Bull. 82, pt. 7, U. S. Bur. luit., p. 85. 

 Feb., 1911.) In other words, the potato beetle, being an important 

 economic insect, has been much studied, and among other things we 

 have learned that it has numerous enemies. If less were known about 

 the species it would be hailed as a marvelous instance of protective 

 adaptation ; facts are a terrible handicap to theorizing. 



Discussion. — In general we have seen that whatever the beetle, 

 something in the way of protective adaptation has been claimed for it, 

 yet practically all are eaten. On the other liand we liave also seen that 



