REPORT OF THE ENTOMOLOGIST. 541 



partment from straws received from Dr. Liiitner, who has referred 

 to this matter publicly in the Country Gentleman, vol. 49, p. 857.* 



In Michigan the same insect appeared in 1884, working in the same 

 way. In the Eural New Yorker for May 9, 1885 (vol. 44, p. 314), 

 Prof. A. J. Cook described it in all stages at some length under the 

 name of '' The Black Wheat-stalk Isosoma" {Isosomamgrum, n. sp.). 

 He stated that he had received it from Wayne and Washtenaw Coun- 

 ties, and that at a "farmers' institute" held at Plymouth, Wayne 

 County, in January, he found hardly a farmer Avho had not been 

 vexed by the small pieces of straw, but that not one had discovered 

 the cause. 



On the appearance of Professor Cook's article we wrote to him for 

 specimens, strongly suspecting that his new species would turn out 

 to be the Common Joint Worm, He kindly complied with our re- 

 quest, and our suspicions were at once verified, and, as stated in our 

 article in the Rural New Yorker (loc. cit.), they proved to be well- 

 marked examples of Fitch's tritici form of I. liordei. Professor 

 Cook is still, we believe, inclined to insist that his species is a good 

 one, but without going into the details of our rather extensive cor- 

 respondence with him in this matter, we reassert the correctness of 

 our conclusion and pronounce the Michigan insect to be I. hordei.f 



In conclusion we may extract a few facts from our notes bearing 

 on the dates of transformations and the prevalence and habits of the 

 parasites: 



December 9, 1884. — Eight straws which were received from Louisa 

 County, Virginia, July 30, were examined, with the following result: 

 No. 1. Two parasites had issued, and the straw still contained three 

 pupge of Isosoma and seven larva3 of a Chalcid parasite. 'No. 2. 

 Five parasites had issued, and seven pp.rasitic larvas still remained. 

 No. 3. Ten parasites had issued, and one pupa of Isosoma; one liv- 

 ing and three dead larvae of the parasite remained. No. 4. Two 

 parasites had issued, and six pup?B of Isosoma, and one parasitic 

 larva. No. 5. One parasite had issued, and three Isosoma pupre and 

 four parasitic larvaa remained. No. 6. Two parasites had issued, and 

 three pupsB of Isosoma and two parasitic larvss remained. No. 7. 

 Contained four Isosoma pupse and three parasitic larvae. No. 8. 

 Five Isosoma pupae and five parasitic larvae. Isosoma was found 

 only in the pupa state. 



On December 17 the adult Isosomas began to issue, and they con- 

 tinued to appear in small numbers through January, February, 

 March, and April, issuing most abundantly the first week in Ma}'-, 

 On May 28 straws were received from Louisa County which con- 

 tained eggs nearly ready to hatch. 



The breeding of 1885-86 was very similar to this, and indicates that 

 the periods mentioned are about normal. The adults of both sexes 



* In the American Agriculturist for December, 1884, vol. 43. p. 531, what is evi- 

 dently the same insect is treated as having been received from " Central New York," 

 and which is there determined as Isosoma tritici, a reproduction of om- figure of that 

 species being also given. 



t Professor Cook later republished the bulk of his first article on the subject as 

 an original contribution to the American Naturalist for September, 1885 (pp. 804- 

 808). Here he seems to be in some doubt as to the validitv of his species and ex- 

 presses the opmion that it ^vill take time to "clear all this up," and savs : "As spe- 

 cies are only venerable varieties which by age have been run into the m'old of varia- 

 bility, it really makes no great difference. Practically the matter remains the same 

 in either case." Such reasoning would justify unlimited species-making from any 

 one species known to be quite variable. 



