journal of tmrnm research 
Vol. XXI Washington, D. C., June 15, 1921 No. 6 
BIOLOGY AND ECONOMIC IMPORTANCE OF ANASTATUS 
SEMIFLAVIDUS, A RECENTLY DESCRIBED EGG PARA¬ 
SITE OF I-IEMILEUCA OLIVIAE 
By D. J. Caffrey 
Scientific Assistant, Cereal and Forage Insect Investigations, Bureau of Entomology, 
United States Department of Agriculture 
INTRODUCTION 1 
Adults of the recently described egg parasite Anastatus semiflavidus 
Gahan were first reared from eggs of the New Mexico range caterpillar, 
Hemileuca oliviae Ckll., during the progress of experiments to determine 
methods for the economic control of that destructive pest. 
These rearings were made by F. H. Gates from Hemileuca oliviae eggs 
collected in the vicinity of Koehler, N. Mex., during June, 1913. For 
several years prior to this date extensive egg collections in the same 
vicinity and throughout the infested area had failed to reveal the pres¬ 
ence of any egg parasite of H. oliviae . 2 It is assumed from the foregoing 
that, just before the period during which these negative collections were 
made, some severe and unusual climatic condition had reduced the num¬ 
bers of the parasite to such an extent that its presence was not discov¬ 
ered at that time. Since its discovery in 1913 the parasite has appeared 
in increasing numbers each year until it now exerts a powerful influence 
in the natural control of its host. 
DISTRIBUTION OF THE PARASITE 
Egg collections made during the autumn of 1915 and the winter and 
spring of 1916 demonstrated that the parasite was widely distributed in 
that part of northeastern New Mexico which was heavily infested by 
the range caterpillar. Adults were reared from the following localities 
in that section: Maxwell, Brackett, Nolan, Las Vegas, Springer, Chico, 
Cimarron, Mora, Watrous, Miami, Colfax, Folsom, Wagon Mound, 
Vermejo, Koehler, Colmor, Taylor, Levy, Roy, Mills, and Clayton. 
1 The observations detailed in this paper were made principally at the United States Range Caterpillar 
Camp near Koehler, N. Mex., and at the United States Entomological Laboratory, Maxwell, N. Mex 
V. L. Wildennuth, F. H. Gates, W. F. Schlupp, and H. E. Smith assisted in securing the data herein 
presented. 
* AlNSLIB, C. N. THB NEW MEXICO RANGE CATERPILLAR (HEMILEUCA OLIVIAE CKLL.)* In U. S. Dept. 
Agr. Bur. Ent. Bui. 85, pt. 5, p. 59-96, fig. 32-53, pi. 3-4. 1910. 
Voi. XXI, No. 6 
June 15, 1921 
Key No. K-95 
Journal of Agricultural Research, 
Washington, D. C. 
yb 
(373) 
