INSECTS IN RELATION TO OTHER ANIMALS 245 



diose records in the orchard were compared with those made elsewhere 

 had eaten in the former situation as many caterpillars other than canker- 

 worms as usual, simply adding their canker-worm ratios to those of other 

 :aterpillars, goes to show that these insects are favorites with a majority 

 >f birds." 



The Relations of Birds to Predaceous and Parasitic Insects. The 

 false assumption is often made that a bird is necessarily inimical to 

 man's interest whenever it destroys a parasitic or a predaceous insect. 

 Weed and Dearborn attack this assumption as follows: 



" Suppose an ichneumon parasite is found in the stomach of a robin 

 or other bird: it may belong to any one of the following categories: 



" i. The primary parasite of an injurious insect. 



"2. The secondary parasite of an injurious insect. 



"3, The primary parasite of an insect feeding on a noxious plant. 



"4. The secondary parasite of an insect feeding on a noxious plant. 



"5. The primary parasite of an insect feeding on a wild plant of no 

 economic value. 



"6. The secondary parasite of an insect feeding on a wild plant of no 

 economic value. 



"7. The primary parasite of a predaceous insect. 



"8. The primary parasite of a spider or a spider's egg. 



"This list might easily be extended still farther, and the assumption 

 that the parasite belongs to the first of these categories is unwarranted 

 by the facts and does violence to the probabilities of the case. 



u A correct idea of the economic role of the feathered tribes may be 

 obtained only by a broader view of nature's methods, a view in which 

 we must ever keep before the mind's eye the fact that all the parts of 

 the organic world, from monad to man, are linked together in a thousand 

 ways, the net result being that unstable equilibrium commonly called 

 'the balance of nature.' ' 



The general subject of food relations and interactions of insects is 

 taken up in the chapter on ecology (page 373). 



Efficiency of Protective Adaptations of Insects. Interesting from 

 a scientific point of view are the various adaptations by means of which 

 insects are protected more or less from their bird enemies. Colora- 

 tional adaptations having been discussed in another chapter, there 

 remain for consideration (i) hairs, (2) stings, (3) odors, flavors and 

 irritants. Most of what follows is from an admirable paper by Dr. Judd, 

 whose data are based upon his examination of the stomach contents of 

 fifteen thousand birds. 



