11 
artificial introductions had been made. The result of the minor 
experiment at McPherson was, as reported by Mr. Knaus, no more 
favorable. 
During the last two weeks of April a great many small lots of 
parasites were distributed over the southern and central counties of 
Kansas by Mr. S. J. Hunter, of the Kansas State University. The 
artificial sending out of these parasites by Mr. Hunter and the test 
of distributing an enormous quantity in a single field, described 
above, were legitimate experiments, but the evidence showed very 
conclusively that they resulted in no benefit whatever. In other 
words, as noted above, the parasites were already infesting 12 per 
cent of the “ green bugs” at Wellington, Kans., April 9, when the 
artificial introduction was made, and 50 to 75 per cent at King- 
fisher, Okla., at the same date, and they were only waiting for 
weather conditions to make it possible for them to do their work. 
Just as soon as the favorable weather arrived the parasites bred enor- 
mously and quickly overcame the “ green bug.” In no case was there 
a field of the hundreds examined in southern Kansas where the para- 
sites natively present did not outnumber by many thousands or hun- 
dreds of thousands any number that could have been introduced 
artificially, at a time when weather conditions had become such that 
the liberations could have had any benefit. As shown by the careful 
investigations of the agents of this Bureau in the field, and independ- 
ently of Prof. E. A. Popenoe, entomologist of the Kansas State 
Agricultural College, and his assistants, the parasites were equally 
abundant in all fields in May, when weather conditions became favor- 
able, irrespective of whether distributions had been made or not. 
The weather, therefore, is the important influence. As demon- 
strated by the experience of this and other years, these parasites, 
always present in limited numbers, will overcome the aphis unaided 
as soon as weather conditions permit, and no artificial introduction. 
great or small, appears to hasten or increase their efficiency. 
The writer left Washington for Kansas May 13 to take personal 
charge of the field work in relation to the “ green bug ” and to make 
a thorough survey of actual field conditions. The “ green bug” at 
this time (May 15) had become abundant in oats as far north as 
Manhattan, Kans.; but wherever present there were numbers of para- 
sites also already in evidence. Indeed, Mr. Phillips found this 
to be true at Kearney, Nebr., which point he visited about a week 
later. In no instance was a field observed, either in the vicinity of 
Manhattan or, during the next week or ten days, anywhere in Kan- 
sas, where the parasite was not present wherever the “ green bug ” 
occurred. 
[Cir. 93] 
