INSECTS IN RELATION TO OTHER ANIMALS 291 
chafer was compensated by a general diminution of the ratios 
of all the other elements, and not by a neglect of one or two 
alone. If the latter had been the case, the criticism might 
easily have been made that the birds, in helping to reduce one 
oscillation, were setting others on foot. 
“3. The fact that, with the exception of the indigo bird, the 
species whose 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 caterpillars, goes 
to show that these insects are favorites with a majority of 
birds.” 
The Relations of Birds to Predaceous and Parasitic In- 
sects.—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 follow- 
ing categories : 
oe 
1. The primary parasite of an injurious insect. 
oe 
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 nox- 
1ous plant. 
“5. Ihe 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 cate- 
gories is unwarranted by the facts and does violence to the 
probabilities of the case. 
