y6 BULLETIN 234 



cations of small or half -grown borers, as there would be if the insect required 

 two seasons to develop. 



NATURAL ENEMIES 



Were it not for the ubiquitous English sparrow, doubtless the woodpeck- 

 ers would help considerably in reducing the numbers of this bronze birch 

 borer. The sparrows have largely driven the woodpeckers out of city parks 

 and private grounds. During most of its life, or for about eleven months 

 in a year, the borer is just under the bark where the birds could easily get at 

 it. Adams observed one of the common woodpeckers, probably the hairy 

 woodpecker, feeding quite extensively upon the grubs in Buffalo. 



The pest does not escape from parasitic enemies. While examining 

 some infested branches of birch in January, 1899, I found several borers that 

 had been killed by parasitic grubs. The parasite had spun a tough, semi- 

 transparent cocoon inside the skin of its host. Later the adult parasite was 

 bred and it proved to be the interesting little creature shown much enlarged in 



FIG. 38. Phasgonophora sulcata. The interesting 1. 1 lie parasitic 

 enemy of the btonze birch borer. Much enlatged. 



Fig. 38. It is a Chalcid fly known to science as Phasgonophora sulcata West- 

 wood (Griffith's Animal Kingdom, Insects, Vol. II, p. 432). Note the won- 

 derful development of the hind legs, the purpose of which is unknown. Chit- 

 tenden also reared the same parasite from this borer and from the flat-headed 

 apple-borer infesting a Japanese redbud tree. The parasites issued about 

 two weeks after the beetles. Dr. Howard writes me that the parasite has 

 been taken in Texas, California, Washington, D. C., Illinois, South Caro- 

 lina, Canada, Florida and Oregon, thus showing a very wide distribution. 

 Doubtless this interesting little enemy aids materially in holding this bronze 

 birch borer in check. But in most localities it has not yet reached that point 

 where it is numerous enough to cope with the pest to the extent that man 

 need not employ artificial agencies to prevent the destruction of his beautiful 

 white birches. 



