LOW TEMPERATURES VS. SCALE INSECTS. 



73 



Results obtained hy exposing orange scale insects, <Jc. — Continued. 



No. of 



•xperiraent 



11 



il- 

 ia 



14 

 1". 

 16 

 17 

 18 

 19 

 20 

 21 

 22 



Minimum 

 tempera- 

 ture. 



Maximum 

 tempera- 

 tare. 



Time of 

 exposure. 



Kesult to 

 larva?. 



Kesult 



Hours. 



1 



u 



2 

 16 

 10 

 12 



5 



11 

 11 



3 



Dead . .. Hatch 



Time from 

 exposure 



to final 

 collapse of 



larva;. 



Days. 

 5 



Remarks. 



..do 



..do 



5 



..do. ... 



..do 



6 



.do 



..do 



o 



..do 



..do 



10 



..do 



..do 



10 



..do.... 



..do 



7, 



..do 



. . do 



6 



..do 



. . do 



3 



..do 



. . do 



3 



..do 



..do 



6 



..do 



..do 



8 



December 26, 18S3. 



During my recent absence from home there was a short period of cold 

 weather, which on my return I found had produced naturally nearly all 

 of the conditions that in my experiments were produced artificially. 



Although I was only 10 miles directly south of here, at the place where 

 I was the effects were very slight, and near by there were no traces of 

 frost, tomatoes and bell peppers out of doors being unhurt. 



Dad I known in time the extent of the damage elsewhere I could have 

 made some valuable observations. 



The thermometer is reported at various figures, ranging from 21° F. 

 to 30° F. The effects show as wide a difference. 



In the same neighborhood I find young orange trees killed to the col- 

 lar at the ground, and orange and lemon trees that are unhurt, and 

 these are sometimes within a few yards of each other. 



Six days after the frost, examination showed that the defoliated 

 branches infested by insects were dead, whilst others not so exposed 

 were living, and that where the small twigs were not killed there were 

 some living eggs. 



I also find the same appearances as in the experiments, eggs dead and 

 living in the same scale. 



The stated probable effects of the initial heat of the tree. &c, are re- 

 alized and very distinctly marked. I inclose a twig showing this. The 

 outer portion is dead, and the eggs are also dead. The basal portion cut 

 from near the body of the tree is living, and there are also thereat this 

 writing some eggs that are clear and pink. 



This cold term was calm, the greatest cold of short duration, not more 

 than an hour. The conditions were as aearly a reproduction of those of 

 the experiments, probably, as ever occurs naturally, and the results are 

 so similar as to give greater value to the information artificially ob- 

 tained. 



Respectfully, 



JOS. YOYI.K. 



Prof. C. Y. Riley, T. n. Entomologist. 



