674 MICHIGAN BIRD LIFE. 



difficulty in taking nesting material into the box with the smaller hole, 

 most of the twigs and grass being dropped on the ground in the effort 

 to get them in. In order to avoid this trouble it is suggested that boxes 

 for wrens be made with the entrance in the form of a slit at least three or 

 four inches in length, but not more than seven-eighths of an inch in width, 

 which will allow the bird to take in any nesting material it pleases, but 

 will still exclude the Sparrow. 



But one serious charge has been made against the Wren, if we except the 

 fact that it is notoriously pugnacious and often attempts to drive other 

 l)irds away from its premises even when they do not seem to be in the 

 least harmful. The fact referred to is that the Wren has been detected 

 several times in the act of destroying the eggs of other birds, puncturing 

 them with its bill, either for the sake of eating the contents, or, as seems 

 more probable, simply out of mischief. A few observers, notably Otto 

 Widmann, of St. Louis, ]\Io., claim that this habit is quite general, but 

 in Michigan our observations do not confirm this view. Although we 

 have had numbers of Wrens nesting about the College campus for the 

 ])ast ten years, in no single instance have we discovered eggs of other 

 birds which had been punctured in this manner. True, eggs of the Robin, 

 Song Sparrow and Blue Jay have been found upon the ground with large 

 holes in them, but there was nothing in any of these cases to indicate that 

 the Wren was concerned in their injury. In one case a Cowbird was seen 

 eating the eggs of a Chipping Sparrow upon the ground, and it seems 

 likely that the Cowbird, the Blue Jay or the Bronzed Grackle, all of which 

 are superabundant in the vicinity, were the real miscreants. 



The food of the Wren consists almost entirely of insects and arachnids, 

 and the species is certainly of great use to the orchardist and gardener in 

 destroying noxious insects. Fifty-two stomachs examined in the Division 

 of Biological Survey, United States Department of Agriculture, and re- 

 ported on by Dr. Judd, contained 4 percent of ants, 16 percent of cater- 

 pillars, 22 percent of beetles, 25 percent of locusts, crickets and grass- 

 hoppers, 12 percent of bugs of various kinds, and 14 percent of spiders 

 and thousandlegs. The total amount of animal food was 98 percent, the 

 remaining 2 percent being vegetable rubbish. "Half the food consists 

 of grasshoppers and beetles; the other half is made up of approximately 

 equal quantities of caterpillars, bugs, and spiders. Several of the most 

 important families of beetles were represented, and among them the 

 omnipresent little ground beetle formed 6 percent; weevils, which amounted 

 to 11 percent of the food in June, ranked next in importance. Wrens eat 

 about half as many little dung beetles as weevils. The former amount to 

 10 percent of the food in May, but are not eaten later in the season. * * * 

 Common grasshoppers, green grasshoppers and crickets form the most 

 important part of the House Wren's food, reaching a maximum of about 

 60 percent in August, and practically excluding many heretofore con- 

 spicuous elements. The Catbird and Thrasher stop eating grasshoppers 

 when fruits ripen, but the Wren keeps right on with the good work."* 



Prof. Aughey states that he has ''watched parents [Wrens] feed their 

 young in a great number of instances in northern and southern Nebraska 

 and in western Iowa during locust years and always found them bringing 

 a great number of small locusts" (1st Rep. U. S. Entom. Com. Appendix 

 2, p. 18). 



Professor Forbes, reporting on Wrens taken in an orchard overrun 



♦Yearbook, U. S. Department of Agriculture, 1895, p. 417. 



