332 Studies in the Theory of Descent. 



I often repeated this experiment, and always 

 with the same result. Once it could be plainly 

 seen that it was really fear and not mere curiosity 

 that the birds showed towards the caterpillar. 

 The latter was outside the trough amongst 

 scattered grains of food, so that from one side it 

 was concealed by the trough. A sparrow flew 

 down obliquely from above, so that at first it could 

 not see the caterpillar, close to which it alighted. 

 The instant it caught sight of the insect, however, 

 it turned in evident fright and flew away. 



Of course these experiments do not prove that 

 the larger insectivorous birds are also afraid of 

 these caterpillars. Although I have not been able 

 to experiment with such birds, I can certainly 

 prove that even fowls have a strong dislike to 

 these insects. I frequently placed a large Elpenor 

 larva in the poultry yard, where it was soon dis- 

 covered, and a fowl would run hastily towards it, 

 but would draw back its head just when about to 

 give a blow with the bill, as soon as it saw the 

 caterpillar closely. The bird would now run round 

 the larva irresolutely in a circle the insect in the 

 meantime assuming its terrifying attitude and 

 stretching out its head would make ten or twenty 

 attempts to deal a blow with its bill, drawing back 

 again each time. All the cocks and hens acted in 

 a similar manner, and it was often five or ten 

 minutes before one particularly courageous bird 

 would give the first peck, which would soon be 



