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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
amount of additional data bearing on resistance has been obtained. 
While it will not be possible to discuss all these data in this paper, it is 
the purpose of the writers to present some of the more significant re¬ 
sults. Two major lines of investigation have been followed: First, to 
determine the relative infestation of different varieties and strains of 
wheat, and second, to determine why certain ones are resistant, or, if 
not, why they escape injury in some cases where others are seriously 
affected. 
Relative Infestation of Different Varieties of Wheat 
The first line of investigation has been conducted to establish the fact 
that resistance does occur and that it is consistent under various con¬ 
ditions. Numerous plantings have been made in the field each year, 
and in the greenhouse in 1920-1921. Over two hundred varieties and 
strains of wheat have been under observation, but, by elimination, 
this number has been reduced to about thirty in order to facilitate the 
work. Oviposition and infestation records have been kept on all 
plantings, and the percentage of infestation in the fall, at harvest, 
and under greenhouse conditions, is summarized in Table 1, (page 295). 
These field and greenhouse tests have established a number of impor¬ 
tant points. (1) There is practically no discrimination by the adult fly 
in ovipositing, since eggs are deposited in large numbers on all varieties. 
(2) There is a great difference in the subsequent infestation, and certain 
varieties exhibit marked resistance. (3) Since several varieties, such as 
Illini Chief, Dawson Golden Chaff, Beechwood Hybrid, Currell Selec¬ 
tion and Dietz, have had very few plants infested in the fall, they may be 
classed as resistant. (4) Other varieties as Turkey, Kharkof, Ghirka, 
Zimmerman, and Marquis, have been very susceptible under all con¬ 
ditions. (5) A few varieties, as Kanred, Clark’s Blackhull, and Ful- 
caster, have been erratic, being apparently resistant in one test and very 
susceptible in another. (6) The soft wheats, as a class, have been 
more resistant than the hard wheats, although one variety of soft 
wheat (Zimmerman) has been decidedly susceptible, while a variety of 
hard wheat (Red Winter 2132) has shown a marked tendency toward 
resistance. (7) The infestation at harvest in most cases has been in 
accord with that in the fall, although in the case of Beechwood Hybrid, 
Rudy, and Illini Chief, there is a tendency towards susceptibility. 
(8) Under abnormal conditions, such as greenhouse tests, the plants in 
general maintain their same relative position with regard to resistance. 
The marked resistance of Illini Chief in the earlier experiments led 
