NO. 7 PROTECTIVE ADAPTATIONS McATEE 57 



(red-eyed vireo and robin) ; and more than 400 times in the following 

 five species: crow (438), starling {72^), meadowlark (474), crow 

 blackbird (600), and English sparrow (466). One hundred or more 

 caterpillars further unidentified were found in single stomach con- 

 tents of each of the following birds: sparrow hawk, downy wood- 

 pecker, hairy woodpecker, black-billed cuckoo, yellow-billed cuckoo, 

 crow, starling, crow blackbird, hermit thrush, wood thrush, and robin. 

 A very characteristic phase of the destruction of caterpillars by birds 

 is their use as a special food for the young ; numerous species of birds 

 make a practice of feeding the young a very much higher proportion 

 of caterpillars than is taken by the adults. 



It has often been asserted that hairs and spines are very effective 

 in protecting certain caterpillars from birds.^ Bastin for instance, 

 states that " stinging hairs defend their possessors from almost all 

 birds except the cuckoos." (Insects, their life-histories and habits, 

 p. 168, 1913.) These claims ignore the fact that birds are very well 

 equipped with relatively insensitive bills and feet for removing spines 

 and hairs from larvae if they choose. Some birds do this, others 

 actually dissect caterpillars, eating parts they want from the inside, 

 piecemeal. Hairy and spiny armature is no bar to birds with such 

 feeding habits, and, furthermore, do not seem to be of any great 

 service in relation to numerous birds which swallow entire larvae thus 

 defended. A characteristic statement about hairy caterpillars is : 



" Tent caterpillars have few enemies Our two species of 



Cuckoos make it a regular business to feed upon these worms which 

 no other birds will eat." (Lugger, Otto, Fourth Ann. Rep. Ent. Minn. 

 (1898), p. 142, 1899.) 



Seventeen of the species of birds included in the tabulations on 

 which this paper is based had eaten tent caterpillars or the eggs from 

 which they hatch ; numbers of larvae taken at a meal ran up as high 

 as 200 in case of the black-billed cuckoo, and of eggs as high as 1,047 

 in that of a blue jay. Compiling records from the reports of ento- 

 mologists and others who have found birds feeding upon tent cater- 

 pillars, we get a list of 43 species of bird predators upon the so-called 

 " Orchard " species (Malacosoma americana) and 32 upon the 

 "Forest" species {M. disstria). Caterpillars even more offensively 



' In the case of this as in other similar claims, we may. well ask wliy such 

 theoretically effective defenses have not been developed hy a larger proportion or 

 in fact by all larvae? The most cursory consideration of the subject shows 

 that hairiness of caterpillars is in the main a phyktic character. A few related 

 families include the great bulk of the hairy larvae. 



