February, '17] McCOLLOCH: UNDERGROUND INSECTS 183 



eggs that show the exit holes of this parasite. These percentages are 

 then charted. From a study of such charts made over a period of 

 years, the increase in percentage of parasitism and the yearly disper- 

 sion is determined. 



I have tried to show by the examples of these two imported parasites, 

 that as their seasonal histories and habits differ, so must the methods 

 of their colonization. It takes time to develop the correct methods to 

 use and if the preliminary work is hurried, much valuable material and 

 information may be lost. The introduction of parasites is simply an 

 attempt to assist in bringing about a proper natural balance in order to 

 hold our imported pests in check. 



The problem is complicated by many factors requiring careful and 

 thorough investigation, if errors are to be avoided. 



President C. Gordon Hewitt: Is there any discussion? 



Miss Brace: Is anj^ provision made for air in the breeding trays? 



Mr. S. S. Grossman: The ti'ays are not air tight but no special 

 arrangement to admit air is necessary. 



President G. Gordon Hewitt: Mr. J. W. McGolloch will present 

 the next paper. 



A METHOD FOR THE STUDY OF UNDERGROUND INSECTS^ 



By James W. McColloch, Assistant Entomologist, Kansas State Agricultural Experi^ 



ment Station 



With the establishment, in 1914, by the Department of Entomology 

 of project No. 100, which deals with a study of those insects injuring 

 the roots and germinating seeds of staple crops, such as white grubs, 

 wireworms, and false wireworms, it was found necessary to devise some 

 methods for rearing the various species concerned. Davis^ describes 

 a number of cages which he has found successful in the rearing of white 

 grubs and the writer, after trying several of them, found the one- 

 and two-ounce salve boxes the most satisfactory, because the individ- 

 ual insects could be followed throughout their growth. During the 

 summer of the first year, an attempt was made to rear the insects in 

 the field insectary, and under compost heaps, as suggested by Davis, 

 during the winter. 



^ Contribution from the Entomological Laboratory, Kansas State Agricultural 

 CoUege, No. 24. This paper embodies some of the results obtained in the prosecution 

 of project No. 100 of the Kansas Agricultural Experiment Station. 



2 Davis, J. J., Cages and Methods of Studying Underground Insects. Jour. Econ. 

 Ent., vol. VIII, 135-139, 1915. 



