228 ENTOMOLOGICAL SOCIETY 



in the main came from Egypt and the adjoining parts of Asia. 

 He mentioned particularly the domestic cat and the domestic dog. 

 Referring to Mr. Ashmead's statement as to the spread of para 

 sites, he incidentally mentioned the house-fly and the bed-bug, 

 whereupon Dr. Merriam stated that he had never known the 

 bed-bug to occur in the boreal zone. " Dr. Gill was inclined to 

 think that he had heard of its occurrence in St. Johns, New 

 foundland, and he remarked that we cannot trust to negative evi 

 dence, such as that just advanced by Dr. Merriam, for upon 

 negative evidence alone he would be inclined to say that the bed 

 bug does not occur in the city of Washington ! Mr. Schwarz 

 stated that the chicken-flea Sarcopsylla gallinacea had re 

 cently been traced by Julius Wagner (Horae Soc. Ent. Ross. 28, 

 1894, pp. 440) to central Asia, which is probably its original 

 home. 



Mr. Marlatt read a paper entitled : 



FURTHER NOTE ON THE CODLING MOTH. 

 By C. L. MARLATT. 



A very interesting and satisfactory explanation of the variation 

 in the number of broods of the Codling Moth in different parts 

 of the United States is given by the maps illustrating Dr. C. 

 Hart Merriam's Laws of Temperature Control of the Geograph 

 ical Distribution of Terrestrial Animals and Plants.* Dr. Mer 

 riam's first map, showing the distribution of the total quantity 

 of heat during the season of growth and reproductive activity, 

 presents an interesting agreement in its zones with the available 

 records in regard to the number of broods of this insect, and gives 

 a basis of fact for my statement, in Insect Life, (vol. VII, No. 

 3, pp. 248-51,) that " it must be inferred that the climate of New 

 Brunswick differs in the summer season sufficiently from that of the 

 middle and western States even of Iowa and northern Illinois 

 to lead to the development of but one yearly brood." The data 

 so far obtained indicates one annual brood for the region over 

 which the total summer heat exceeds 5,500 C., corresponding 

 pretty closely with Dr. Merriam's transitional zone, and includ 

 ing, in general, the northern tier of States, with a southward ex 

 tension along the main mountain systems, most of New England, 

 and northern New Jersey. Two annual broods may be expected 



* National Geographical Magazine, vol. VII, pp. 229-238; pi. XII-XIV. 



