127 
n the examinations thus far made, I had not been able to find 
7 instance which should exactly test the hypothesis that the injury 
ler examination was due to the insect only. In every case where 
i fields were contrasted, there was some additional difference 
ween them than that of abundance or scarcity of the plant bug; 
ler a difference in variety, in location, in treatment, or in the 
ount of rust occurring. The first fields visited at Centralia, how- 
r, gave me the example I had been seeking. 
-Wo large fields of Wilsons, of the same age, separated only by a 
3et, upon soil of precisely the same character, mulched‘ alike, 
l otherwise treated identically, as I was informed by Mr. Brunton, 
*e found to differ to a marked degree, at least in the places ex¬ 
ited, with respect to the amount of buttoning apparent. In one 
d the berries were in very good condition, while in the other, 
f or more of those examined were buttoned and deformed. In 
former, seventy-five strokes of the net gave thirty-one insects; 
[ in the latter, fifty strokes gave eighty-nine. 
next examined a field belonging to Mr. Brunton, containing 
scents, Downings and Wilsons, all on new ground, and also a 
| ch of Wilsons which had been in berries previously. These were 
side by side, and of the same age and previous history. In the 
scents no injury was observed, nor yet in the Wilsons adjoining. 
M Downings were considerably injured, and the Wilsons in that 
i t of the field which had been in strawberries previously were 
ly buttoned. In the uninjured Wilsons, twenty-five sweeps of the 
gave but seven bugs; and in the injured Wilsons, fifty sweeps 
e twenty. In the Downings, which were considerably buttoned, 
/ sweeps yielded forty insects; and in the badly injured Wilsons, 
nty-five sweeps gave sixty. Another field of Wilsons, a little 
i oved from these, somewhat damaged, but not badly, yielded 
ty bugs to twenty-five sweeps. The plants in all these fields 
e more or less affected by rust, but in about equal ratio. A 
nber of other fields of Wilsons were examined, but the results 
e so strictly identical with those already given that it is not 
assary to narrate them in detail. 
, 
he fact has already been mentioned of the occurrence of another 
lies, the dusky plant bug, Derceocoris rapidus, in the same fields 
l Lygus lineolaris. Although generally much less abundant than 
other, in some fields at Centralia its numbers amounted to a 
d or fourth those of Lygus. Everywhere both were in the same 
:es, and were evidently working upon the berries in precisely the 
e manner; consequently in the preceding details respecting the 
! iber of plant bugs present, both species have been included. A 
irate discussion of Derasocoris is, however, given elsewhere. 
Ithough many other plants were of course present in the straw- 
i y fields, these plant bugs were only occasionally seen upon any 
hem. In one field of Mr. Earle’s, in which the insect swarmed, 
kberries were placed in alternate rows with the strawberries, but 
as a very unusual thing to find the insects upon a blackberry 
'\i. 
i 
ft 
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