ii.] EYE SPOTS OF CATERPILLARS. 59 



Moreover, the ring on which they are placed is swollen, 

 and the insect, when in danger, has the habifc of re- 

 tracting its head and front segments, which gives it an 

 additional resemblance to some small reptile. That 



FIG. 44. Chcerocampa porcellus. 



small birds are, as a matter of fact, afraid of these 

 caterpillars (which, however, I need not say, are in 

 reality altogether harmless) Weissmann has proved by 

 actual experiment. He put one of these caterpillars in a 

 tray, in which he was accustomed to place seed for birds. 

 Soon a little flock of sparrows and other small birds 

 assembled to feed as usual. One of them lit on the 

 edge of this tray, and was just going to hop in, when 

 she spied the caterpillar. Immediately she began 

 bobbing her head up and down, but was afraid to go 

 nearer. Another joined her, and then another, until at 

 last there was a little company of ten or twelve birds, 

 all looking on in astonishment, but not one ventured into 

 the tray ; while one bird, which lit in it unsuspectingly, 

 beat a hasty retreat in evident alarm as soon as she per- 

 ceived the caterpillar. After watching for some time, 

 Weissmann removed it, when the birds soon attacked the 

 seeds. Other caterpillars also are probably protected by 

 their curious resemblance to spotted snakes. 



Moreover, as Weissmann points out, we may learn 

 another very interesting lesson from these caterpillars. 

 They leave the egg, as we have seen, a plain green, like 



