The Bronze Birch Borer. Igt 



The pest does not escape from parasitic enemies. While examining 

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

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

 semi-transparent cocoon inside the skin of its host. J^ater the adult para- 

 site was bred and it proved to be the interesting little creature shown 

 much enlarged in Fig. 38. It is a Chalcid fly known to science as Phas- 

 gonophora sulcata Westwood (Griffith's Animal Kingdom, Insects, \o\. 

 II, p. 432). Note the wonderful development of the hind legs, the 

 purpose of which is unknown. Chittenden 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 Carolina, Canada, Florida and Oregon, 

 thus showing a very wide distribution. Doubtless this interesting little 



Fig. 3S. — Phasgonophora sulcata. The interesting little parasitic 

 enemy of the bronze birch borer. Much enlarged. 



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. 



Remedial Suggestions. 



This bronze birch borer is practically invulnerable against man's 

 usual insecticides. Nearly all of its life is spent as a borer under the 

 bark out of reach of insecticides. The fact that the beetles feed for a 

 few days on tender leaves would suggest spraying the trees in ]\Iay with 

 a poison, but apparently they do not eat the birch foliage to any extent, 

 preferring that of willow, poplar, or elm. Thus it is very doubtful if it 

 would materially check the insect to spray the birches with a poison. 



On account of the possibility that the beetles might be prevented from 

 emerging or from laying their eggs, several applications to the bark have 

 been suggested, such as a poisoned whitewash, a mixture of hydraulic 

 cement and skim milk, covering the trunks with a paper wrapping, and 



