
Relative 
Date of treatment Temperature humidity Kill 
eed a Percent ' Percent 
Sept. 6 81 fe 90 
; i= Bo?” 74 94 
ral 68 76 5 
4°) 76 70 20 
Oct. 4 fee 78 20 

west.-~M. C. Lane, of the Walla Walla, Wash., laboratory, reports: 
"The abnormally mild weather has resulted in exceptionally early ap- 
pearance of the elaterid beetles. «a heavy flight of Pheletes canus 
Lec. males occurred shortly after the middle of March, though soil 
temperatures were not such as to cause many females to emerge. A few 
Specimens of other species have been seen, the most important being 
Pheletes californicus Mann., Limonius infuscatus Mots., two species 
of Cardiophorus, and Melanotus oregonensis Lec. The host relation- 
shi;) of the adults is up »set since both pear and cherry trees are in 
full bloom now, whereas the flight cf female P. canus has not begun, 
yet it does not seem possible that the flight of the latter can be 
delayed until the flower hesds of the rhubarb have developed. The 
bloom of the vear, cherry, and rhubarb have, in previous years, been 
the most important sources of fo.d for the adults of P. canus. A 
new host relationshi» may develo, this season, as a result of abnormal 
seasonal conditions." 
Role of temperature and moisture in naphthalene fumigation for 
wireworms.--As a result of exveriments to determine the efficiency of 
naphthalene as a soil fumigant at Walla Walla, Wash., R. S. Lehman re- 
ports that there was no significant difference in wireworm mortality 
in soils where the moisture varied from 8.52 to 28.64 »ercent, and 
there was practically no difference in wireworm mortality at 15° C. 
(590 F.) and 25° C. (77° F.) in a 48-hour exposure period. In a 24- 
hour exposure period the mortality at 25° C. was much greater than at 
18° C. When fumigation with na»hthalene takes place in the field the 
conditions are very different then in the laboratory. In the labora- 
tory the naphthalene and wireworms are confined in a closed space with 
no chance for escape of either. If the period of exposure is long 
enuugh, a sufficiently high concentration of the gus is built up to 
kill the wireworms, even at a fairly low temperature. In the field 
the case is somewhat different. If a small quantity of naphthalene 
is used st 4 hiph temperature the gas escapes from the soil before a 
lethal concentration is reached. If a large quantity is used at a low 
temperature the sume thing will occur, that is, the naphthalene will 
escana from the soil gradually as it slowly vaporizes and before a 
lethal concentration is reached. Therefore, the amoumt of naphthalene 
must be such that at a tempereture of 200 to 25° C. (68° to 77° F.) a 
lethal concentration is built up rapidly. From past ex,erience in the 
field it appears that the correct amount is about 800 pounds per acre. 
The species of wireworm involved was Pheletes cunus Lec. 

