112 U8EFUL BIRDS. 



caterjjillars (^Leucarctia acrm(i), the caterpillar of the vaporer moth 

 (^Orgyia) and the spiny Iarv:\3 of butterflies; with these jjerhaps naay 

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

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

 mechanical trouljlesomeness of the hairs prevents their being eaten. 

 Larvae which spin webs, and are gregarious, are eaten by birds, but not 

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

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

 When branches covered with the web of Hyponoinenta evonyrnella (a 

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

 larvte only which ventured beyond the jjrotection 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 vvliose habits are nocturnal, 

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

 the greatest avidity. Every species of green caterpillar is also much 

 relished. All Geometra3, whose larvjie resemble twigs, as they stand 

 out from tlie plant on their anal j^rolegs, 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 hahy 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 \\\y o})portunities for investigating 

 this subject probably 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 difBcult to dis- 

 prove them. A naturalist ma}^ with propriet}^ say what 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 oftencr given, in 

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

 further modification. We cannot rely on results secured by 



» 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. 



