102 The Food of Birds. 



predaceoiis thousand-legs (Geophilus), and two had eaten 

 earthworms (five per cent.). The infrequent occurrence 

 of the last in the stomachs of robins surprised me. It is 

 probably due partly to the greater digestil)ility of these 

 soft worms as compared with the chitinized skins of insect 

 larvae, and partly to the fact that the greater part of those 

 taken by the robin are fed to the young. A few sumach 

 berries eaten by the woodland robins shot in northern 

 Illinois complete the dietary of the month. 



The April food of the robin is, therefore, especially 

 noticeable for the greatly diminishing number of Bibio 

 larv^ and the excessive number of beetles eaten, especial- 

 ly of the Carabidpe and Scarabaedias. 



May. 

 Fourteen birds were studied for this month, all but two 

 of them from various parts of northern Illinois. The rec- 

 ord of May is substantially a duplicate of the April list, 

 except in a few particulars. The Bibio larvas are replaced 

 by seven per cent, of adult crane-flies (Tipulidae) and the 

 Carabidfe drop to four per cent., the balance being almost 

 exactly replaced by the scavenger beetles and leaf-chafers 

 added. Ohlaenius and Agonoderus partiarius are among 

 the captures of these birds. Lachnosterna rises to its 

 highest point in May, and is represented by seventeen per 

 cent, of the food. Wireworms (Elaterida?) are likewise 

 unusually abundant, for some unexplained reason, amount- 

 ing to eight per cent. A single robin had eaten a single 

 potato beetle {Chrysojnela 10-lineata)., and one had taken 

 a specimen of Prometopia ^-maculata. Cwnus delius ap- 

 pears among the Pentatomidae and Polydesmus among the 

 thousand-legs; and sumach berries again occur. 



Ju n e . 

 With June the robin revolutionizes his commissariat. The 

 insect ratios, which have averaged ninety-five per cent, dur- 

 ing the preceding months, now drop to forty-two, and re- 

 main at or below this point for the rest of the year ; and this 

 lack is compensated by the appearance of fifty-five per 

 cent, of cherries and raspberries. The loss falls chiefly up- 

 on the Diptera and Coleoptera, the former dropping from 



