86 The Wilson Bulletin — No. 79. 



nestling period is compensated in the calculation by those in- 

 sects missed in the data for the last half. The fledglings were 

 observed around the ravine as late as July 25 to be positively 

 identified. As it is certain that the daily consumption of in- 

 sects did not diminish to any marked extent, the value of these 

 birds as insect destroyers may readily be inferred. The four 

 insects consumed in the largest quantities were found to be 

 as follows: grasshoppers 247, Mayflies 425, moths 237, and 

 cutworms 103. Two of thesC; at least, are positively destruct- 

 ive insects; and in the summer of 1911 the grasshoppers were 

 almost a plague in parts of northern Iowa. Alany fields of 

 grain were destroyed and many more were cut green to pre- 

 vent destruction, making the oats light weight and of poor 

 quality. The grasshoppers stripped the oats from the straw 

 by cutting the stem of each grain. This was done while the 

 grain was in the milk, so it was a total loss. Many fields 

 which promised from thirty to forty bushels yielded from five 

 to ten bushels to the acre after the grasshopper invasion. As 

 twenty per cent of the food of this family of thrasher con- 

 sisted of grasshoppers, it can readily be seen this species 

 is of considerable economic importance. A glance at the rest 

 of the list will show that almost without exception, the insects 

 fed to the young were of an injurious character. The feed- 

 ing of the raisins was for a time a puzzle to all, and at first 

 they were not recognized as raisins ; but after being brought 

 several times they were identified. The next question w'as as 

 to the source of supply. It was observed that only the fe- 

 male brought them. A careful watch was kept around the 

 buildmgs and she was seen to pick something out of the grass 

 by the kitchen door. On investigation a quantity of raisins 

 was found there and it was learned that a box of them had 

 been accidentally spilled a few days before. The male was 

 not observed to bring any, and as an experiment, a few were 

 placed near the nest. He paid no attention to them for a 

 number of visits, but finally he picked at one several times ; 

 then picked it up, carried it to the fence and swallowed it. 

 He made no attempt to feed them to the young, although sev- 



