442 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1931 



to the species considered. But whether they are in themselves suffi- 

 cient to keep to an insignificant minimum the economic loss occa- 

 sioned by their host, or must be supplemented by other methods of 

 control, our friends, the parasitic insects, constitute one significant 

 ally of man. Their importance does not permit them to be omitted 

 from any program of control for foreign introduced pests, and 

 furthermore, it may be truthfully said that the appreciation of the 

 possibility of their use against native pests has probably only begun. 



LITERATURE CITED 



(1) Howard, L. O., and Fiske, W. F., The importation Into the United States 

 of the parasites of tlie gipsj^ motli aud the brown-tail luoth. U. S. Bur. Ent., 

 n. s. Bull. 91, 344 pp., 1911. 



(2) Howard, L. O., Journ. Econ. Ent., vol. 19, p. 282, 1926. 



(3) Yearbook, U. S. Dep. Agr., p. 14, 1916. 



(4) Smith, H. S., Journ. Econ. Ent, vol. 19, p. 294, 1926. 



(5) Chamberlin, T. R., Journ. Econ. Ent., vol. 19, p. 304, 1926. 



(6) Burgess, A. F., Journ. Econ. Ent., vol. 19, p. 291, 1926. 



(7) Clausen, C. P., and King, J. L., U. S. Dep. Agr., Bull. 1429, 1927. 



(8) Caffrey, D. J., and Worthley, L. H., U. S. Dep. Agr., Bull. 1476, 1927. 



