﻿THE CITRUS MEALY BUG 315 



Experiment: 



Degrees of Temperature Exposure 



F. C. No. of Seconds Results 



92 33.3 20 None killed. Many crawling. 



98 36.6 20 



100 37.7 20 



110 43.3 20 " " None " 



120 48.8 20 



130 54.4 20 Nearly all of the young and many 



adults killed. Eggs unharmed. 

 140 60 20 Nearly all of the young and many 



adults killed. Eggs unharmed. 

 150 65.5 20 All of young and most of the adults 



killed. Only a few eggs destroyed. 

 154 67.7 20 Two living individuals, out of many 



hundreds found. Many eggs still 



fertile. 

 162 72.2 20 Only a few of the large egg-masses 



with fertile eggs. 

 164 73.3 20 No life. 



170 76.6 20 ■' " 



The tests were carried up to boiling point, but no life in any form existed 

 after 164° F. or 73.3° C. had been passed. For dipping boxes, I am recom- 

 mending 170° F, or 76.6° C. in order to make sure of all of the eggs, which 

 may be unusually well protected. 



Fumigation. — The power to resist hydrocyanic acid gas, has been very 

 <lefinitely established in work here. (See Pomona Journal Vol. 1, No. 4, p. 

 1, and Vol. 2, No. 3, p. 246). The very youngest forms, including those of 

 the first moult, first succumb and all of these may be destroyed with a very 

 small dosage. The full-grown adult comes next, while the eggs and the 

 half-grown forms are most resistant. The length of exposure which gave the 

 best results was 2 hours, and the dosage, double Schedule No. 1, administered 

 at the beginning of each hour. An air-tight tent, or an excessive dosage 

 is not sufficient to kill all forms. 



Sprayi)ig. No spray is practical that will not penetrate the cottony cover- 

 ing. The mealy bugs have great resistive power to everything but very 

 penetrating oil or acid sprays. (See Pomona Journal Vol. II, No. 4, p. 246). 



It might be said, in conclusion, that the mealy bug is a great resister, 

 /))(/ it can not effectually resist any systematic methods which arc cncrgcticallv 

 and persistently waged against it. 



Birds. — Without doubt birds play a very important part in the distribution 

 of scale insects. The fact that the orchard trees serve as roosting places for 

 countless numbers of them, afford excellent opportunities for the young scale 

 to crawl upon the feet and legs and be carried to other localities. The in- 

 herent tendency of most insects is to crawl up and there is no choice for the 

 first broods but to do this, regardless of what they may be ascending. Then, 

 too, if a bird alights in a tree which is thickly infested with mealy bug, 

 and ever touches an egg-mass, it is sure to carry .some of it awav, for the 



