2l6 



THE AMERICAN ENTOMOLOGIST. 



worm and the eggs of grasshoppers.* 

 Surely this first bird has not distinguished 

 itself by its possibly well meant, but, at 

 any rate, very unfortunate attack on the 

 insects of the field. 



Taking the month together, we find that 

 the most important elements of the food 

 were cutworms and ichneumons — 24 per 

 cent, of the former to 22 per cent, of the 

 latter. The larvae of the soldier beetles 

 amount to 8 per cent., locusts (chiefly the 

 young of Tragocephahi viridifasciata) to 9 

 per cent^ Carabid beetles and their larvae 

 (including Aj/uira and Anisodactylus) to 5 

 per cent., Cydnidcs. or Soldier-bugs (chiefly 

 Euschistus serviis) to 7 per cent., spiders to 4 

 per cent., and lulidx (thousand-legs) to 3 

 per cent. Other items are, 2 per cent, 

 caterpillars of Arctians {Calli/norp/ui le- 

 contei), 4 per cent, crickets, and 9 per cent, 

 dung beetles {Aphodius fiinetarius and A. 

 inquinatus). The ichneumons, Carabid bee- 

 tles, soldier bugs, and spiders, thus make 

 up 46 per cent, of beneficial insects, while 

 the caterpillars and Orthoptera amount to 

 but 41 percent, of injurious species. Or, 

 if we drop the Cydnidcc from the former 

 category, on account of the supposed tri- 

 fling injuries to vegetation done by some 

 of them (hence often called " plant bugs"), 

 the figures will stand, beneficial insects 39 

 to 41 injurious. But this is not all. Mr. 

 Walsh, reasoning from the comparative 

 numbers of injurious and beneficial in- 

 sects, concludes that a bird must be shown 

 to eat at least thirty times as many inju- 

 rious individuals as beneficial before it can 

 be considered useful ;f but at five times 

 as many, or even twice as many, these 

 bluebirds fall far short of establishing their 

 claim to recognition as defenders of the 

 farm and garden. 



MARCH. 



Twenty-one specimens were examined 

 which had been shot in this month, in 

 1880, ranging from the 7th to the 31st. 

 Seven of these were shot at Normal, nine 

 at Hey worth (15 miles south), and five at 



* See 4th Rept. State Entomol. of Mo., p. 29, and Rent 

 U. S. Ent. Com. 1877, p. 302. uivepi. 



^ Birds vs. Insects. Practical Entomologist, vol. 2 nn 

 44—47. ' ^^' 



Galena, in extreme north-western Illinois. 

 These latter differed from the central Illi- 

 nois specimens chiefly in the presence of 

 the dried and sometimes moldy fruit of 

 the sumach {Rhus glabra) in their stomachs, 

 indicating a scarcity of desirable food at 

 that early season. One of these, unfortu- 

 nately for the record of the month, had 

 stuffed itself with the larvae of Harpaius, 

 which made 93 per cent, of its food. 



Ichncumonidce {Arenetrd) appear again 

 (4 per cent.) for the last time during the 

 season. 



Harpalid beetles and their larvae were 

 unusually abundant, making up 1 1 per 

 cent, of the food of the month. Among 

 these, Flatynus, Evarthrus, Pterostichus, 

 Amara, C/dcEfiius tomentosus, Agonoderus, 

 and Harpaius were recognized. The larvae 

 of soldier beetles also occur, constituting 

 4 per cent, of the food, but do not appear 

 again throughout the year. Four birds 

 had eaten a predaceous bug {Coriscus, near 

 ferns), which is too minute to figure in the 

 ratios ; and 4 per cent, of the food was 

 Cydnidcc, of which only Pcribalus modestus 

 was recognizable. Sixteen of the twenty- 

 one birds had eaten spiders, making 5 per 

 cent, of the food. The beneficial insects 

 thus amount to 28 per cent. On the other 

 hand, 38 per cent, was caterpillars (chiefly 

 Noctuidce*), including Callimorpha lecontei, 

 and the army worm {Lcucania unipuncta), 

 I percent, was Euryomia i//da, and 21 per 

 cent, was Orthoptera (crickets and grass- 

 hoppers), the injurious species thus rising 

 to 60 per cent. One bird had also eaten 

 a minute curculio. Among neutral ele- 

 ments we enumerate Aphodii 3 per cent., 

 Iididce 3 per cent., and sumach berries 4 

 per cent. Two birds had eaten ants, but 

 in trivial quantity. 



In order to determine the number of 

 specimens which it is necessary to examine 

 in each month, to reach reliable averages 

 of benefit and injury, I divided my notes 

 on twenty of the specimens for March, 

 into two groups of ten each, so selected 



* I have thus reported all smooth caterpillars in which the 

 cervical and anal shields, common to most cut-worms, were 

 distinguished. A few such caterpillars are not Noctuids, but 

 all are equally injurious. 



