JTebruaky 4, 1910] 



SCIENCE 



191 



shown by pages 13 to 30 of the bulletin. The 

 eighth, Agent Sanborn, of the Federal Bureau, 

 who had been working by assignment on this 

 problem for a year previous, was present at the 

 original outbreak in Texas and made personal 

 observations back and forth from central 

 Texas through Oklahoma to central Kansas. 



The pertinent portions of these various 

 field observations are to be found on the 

 pages just cited, and all agree without quali- 

 fications that Toxoptera graminum had been 

 vanquished by L. tritici. Moreover, every 

 ■entomologist whose observations on this undue 

 multiplication of T. graminum have since 

 heen published agree on this point. 



From the information, then, at hand bearing 

 upon the statement, " That this parasite not 

 only controlled, but in many cases practically 

 ■exterminated, the green bug last season no one 

 questions," it would seem that, with the ex- 

 ception of the reviewer, this statement main- 

 tains. 



2. The reviewer suggests the probability of 

 the disappearance of the green bug being due 

 to meteorological influences and cites from the 

 report to show that climatic conditions inim- 

 ical to the green bug do arise. Such condi- 

 tions do arise, but, as Glenn has shown later 

 in this report (pages 176 and 180), it is the 

 extremes of summer and winter temperature 

 that affect the green bug, while the struggle 

 between these forms took place and was de- 

 cided during April and May, within which 

 i;ime, as the records show, no such inimical 

 climatic conditions existed. 



3. On pages 150-155 of this bulletin it was 

 shovm in the laboratory experiments that L. 

 tritici did parasitize certain aphids other than 

 T. graminum. On page 156 the original de- 

 scription of L. tritici Ashmead is published, 

 in which appears, "Eeared June 20, 1882, 

 from wheat Aphis, Aphis avenm." There does 

 not, then, seem to be any evidence in this bul- 

 letin to support the reviewer's inference, that, 

 " He [the author] considers the parasite to 

 'belong particularly with this species of 

 Aphid." 



4. In referring, however, to whether Lysi- 

 phlehus maintains a general distribution on 

 these other hosts the reviewer calls attention to 



a pertinent question. The author believed and 

 so stated many times during this outbreak 

 prior to the middle of April, that this para- 

 site existed quite generally over the country, 

 supposedly on other aphid hosts. The au- 

 thor's opinion was modified during April by 

 the cumulation of the following data: 

 (Pages 31 and 32.) 



(a) The green bug was present in Kansas 

 in December, 1906. 



(&) During the first two weeks of April, 

 eight widely separated localities throughout 

 the wheat area of the state showed parasites 

 present in but one place, and subsequent ex- 

 amination proved that to be a, spot of very 

 small area. 



(c) During the same period of April an ex- 

 pert from the Federal Bureau of Entomology, 

 sent here to study the situation, examined 

 wheat fields in nine different parts of the 

 state (Kansas) and found those places free 

 from parasites, except at one point on the 

 southern border, where, he states, " they are 

 beginning to appear." 



(d) Field experiments showed that para- 

 sites were absent until introduced. 



(Pages 29 and 30.) 



(e) Sanborn reported that T. graminum 

 had continued to multiply during December 

 and January over a comparatively large area 

 of northern Texas under conditions favorable 

 to the existence of the parasite and yet no 

 parasite had appeared. 



Then, later in the season, further evidence 

 tended to confirm the opinion that T. gram- 

 inum did not maintain a general distribution 

 on other aphids: First, early in June, after 

 weather favorable to both the artificial and 

 natural distribution of the parasites, a con- 

 servative, trained observer found a large area 

 in the northern part of the state (Kansas) 

 where green bugs were present, but parasites, 

 with one possible exception, only where intro- 

 duced. Second, a serious outbreak of the 

 green bug was reported from Washington, 

 D. C, unattended by the parasite, and this at 

 the close of July, a season most favorable for 

 the activities of the parasite (page 32). 



Since the meteorological conditions of the 

 spring of 1907 were unusual, the author was 



