59 



If we adopt twenty collections as our minimum number from any 

 kind of tree we may make a list of our common forest, shade, and 

 ornamental trees in the order of their attractiveness to May-beetles. 

 In the following, the number after each name is the average number 

 of beetles per collection taken by us from that tree : oak, 79 ; per- 

 simmon, 77 ; poplar, 73 ; hickory, 42 ; willow, 40 ; walnut, 34 ; linden, 

 19; maple, 19; elm, 18; hawthorn, 16; ash, 12; hackberry, 10; box- 

 elder, 5; honey-locust, 4. Making due allowance for the unequal 

 character of the collections unit necessarily used in the computation 

 of my averages, I think there can be no reasonable question of the 

 general meaning of the facts represented by this list, and that we may 

 rely upon these index numbers sufficiently to divide the trees of this 

 list into about five groups, as follows: (a) oak, poplar, persimmon; 

 (b) hickory, willow, and possibly walnut; (c) elm, linden, maple, and 

 birch; (d) ash, hackberry, and hawthorn; and (e) honey-locust and 

 box-elder. Perhaps the only things to regret in this list are the ap- 

 parent marked preference of May-beetles for the oaks and the indif- 

 ference of these insects to the box-elder. While our field notes do not 

 make sufficient mention of the various species of oaks to enable me to 

 recognize differences among them as food for May -beetles, some of the 

 most experienced and observant of my collectors tell me that the 

 shingle-oak (Quercus imbricaria) and the oaks with rounded lobes to 

 the leaves, like the white and bur oaks, are much more resorted to by 

 the beetles than are the red, black, and pin oaks, and other species 

 the lobes of whose leaves are pointed or bristle-tipped. The most 

 dangerous tree on our list is the poplar or cottonwood, of which the 

 much used Carolina poplar is simply a variety. Certainly in the 

 linden, maple, elm, hawthorn, ash, hackberry, and honey-locust, to 

 which we may probably add the red oak and the pin-oak, we have a 

 sufficient variety of fairly safe trees from which to choose for planting 

 either on the village lawn, the country roadside, or the rural home 

 premises. 



