1925] Efficiency of Birds in Destroying Larvce of Corn Borer 33 
caused by migration of a few larvae and the loss of small pieces 
of stalks containing larvae during transportation of the corn- 
stalks used in the experiment. 
The average winter mortality in the 18 experiments listed 
in table No. 1 was 10.5% percent. The average per cent of larvae 
credited to bird feeding in the five stations where stalks were 
attacked, was 61. The average per cent of larvae credited to 
bird feeding in the 18 stations recovered was 17. 
The stations that showed extensive feeding by birds (Fig. 1) 
are all within the area most heavily infested by the European 
corn borer and localities where infestation has been severe for 
several years. Because of this fact and because no marked 
evidence of bird feeding was found in areas slightly infested or 
areas that had become heavily infested by the insect within the 
last year or two, it would appear that woodpeckers are aware 
of the fact that infested cornstalks contain desirable food only in 
this heavily infested area, and that in more sparsely infested 
regions or in areas where infestation had but recently become 
severe they are for the most part still unfamiliar with the exis- 
tence of this source of food. 
Several of the more commonly infested weeds and cul- 
tivated plants were also tied to stakes to observe possible feeding 
by birds on larvse contained in such plants. These were placed 
with the experiment at Medford, Mass., mentioned in Table 1, 
where birds took 69 per cent of the larvse from the cornstalks 
tied to stakes. 
Of the several plants thus observed, common sunflower 
(. Helianthus annuus L.), Princesplume ( Polygonum orientate L.), 
Polygonum sp., and cocklebur ( Xanthium spp.) showed extensive 
feeding by birds of the same sort attributed to woodpeckers while 
no evidence of such feeding was noticed in Abutilon ( Abutilon 
theophrasti Medic.), pigweed ( Amaranthus retroflexus L.), rag- 
weed (. Ambrosia sp.,) beggar-ticks ( Bidens sp.), pot-marigold 
( Calendula officinalis L.), aster ( Callistephus sp.), feather cocks- 
comb ( Celosia argentea L.), Cosmos bipinnatus Cav., Dahlia sp., 
barnyard grass ( Echinochloa crusgalli L.), Japanese millet ( Echi - 
nochloa sp.), Gladiolus sp., strawflower ( Helichrysum bracteatum 
