112 USEFUL BIRDS. 



caterpillars (^Leucarctia acrcea), the caterpillar of the vaporer moth 

 ( Orgi/in) and the spiny larv:i3 of buttei-flies ; with these perhaps may 

 be classed the European currant sawfly. He was disposed to consider 

 the "flavor of all these caterpillars as nauseous, and not that the 

 mechanical troublesomeness of the hairs prevents their being eaten. 

 Larv;^ which spin webs, and are gregarious, are eaten by birds, but not 

 witli avidity ; they appear very much to dislike the web sticking to their 

 beaks, and those completely concealed in the web are left unmolested. 

 When branches covered with the web of IIi/jMHomenta evonymella (a 

 little moth of the Tinea family) were introduced into the aviary, those 

 larva? only which ventured beyond the jH-otection of the web were eaten." 

 " Smooth-skinned, gaily colored caterpillars (such as the currant Abraxas 

 or spanworm), which never conceal themselves, but, on the contrary, 

 appear to court observation," were not touched by the birds. He states, 

 on the other hand, that "all caterpillars whose habits are nocturnal, 

 and are dull colored, Avith fleshy bodies and smooth skins, are eaten with 

 the greatest avidity. Ever}^ species of green caterpillar is also much 

 relished. All Geometroe, whose larva? resemble twigs, as they stand 

 out from the plant on their anal prolegs, are invariably eaten."* 



Such statements as these are at least interesting, but they 

 must be classed as negative evidence, and cannot justify the 

 assertions so often made that birds do not eat hairy cater- 

 pillars, when there is convincing, positive evidence that cer- 

 tain species do eat them. This statement that birds do not 

 eat such caterpillars, which has been so long reiterated, 

 parrot-like, by one writer after another, is entirely at variance 

 with my experience, and my o})portunities for investigating 

 this subject prol)ably have been better than those of most 

 observers. The great burden of proof is upon those who 

 make the allegation, for it is always hard to prove such 

 sweeping generalizations, and often not at all difficult to dis- 

 prove them. A naturalist may with propriety say Avhat he 

 has seen a bird do, but he should be cautious in stating what 

 it does not do. The reiterated assertion that hairy cater- 

 pillars are innnune from the attacks of birds has been modi- 

 fied of late by some writers, and is now oftener given, in 

 effect, that few birds eat them ; but this statement needs still 

 further modification. We cannot rely on results secured by 



1 First Report on Injurious and Beneficial Insects of Massachusetts, by A. S. 

 Packard. Annual Report of the Massachusetts State Board of Agriculture, 

 1870-71, pp. 358, 359. 



