102 
The Food of Birds. 
do the Araclmida (one per cent.). One bird had eaten a 
predaceous thousand-legs (Geophilus), and two had eat- 
en earthworms (five per cent.) The infrequent occur- 
rence of the last in the stomachs of robins surprised me. 
It is probably due partly to the greater digestibility 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 
larvae and the excessive number of beetles eaten, espe- 
cially of the Carabidae and Scarabaeidae. 
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 larvae are re- 
placed by seven per cent, of adult crane-flies (Tipulidae) 
and the Carabidae drop to four per cent., the balance be- 
ing almost exactly replaced by the scavenger beetles and 
leaf-chafers added. Chlaenius 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 (Flateridae) 
are likewise unusually abundant, for some unexplained 
reason, amounting to eight per cent. A single robin had 
eaten a single potato beetle ( Chrysomela 10 -lineata), 
and one had taken a specimen of Prometopia 6-maculata . 
Coenus delius appears among the Pentatomidae and 
Polydesmus among the thousand-legs; and sumach ber- 
ries again occur. 
June. 
With June the robin revolutionizes his commissariat. 
The insect ratios, which have averaged ninety-five per 
cent, during the preceding months, now drop to forty- 
two, and remain at or below this point for the rest of the 
year; and this lack is compensated by the appearance of 
