October, ’24] 
SCIENTIFIC NOTES 
605 
19°F. was recorded in New Orleans, much of the sub-tropical vegetation was severe¬ 
ly frozen and many of the more tender plants killed. 
In connection with the semi-weekly studies of the seasonal history of the camphor 
scale, Pseudaonidia duplex (Ckll.), on camphor trees, data secured on the mortality 
of the insects from natural causes, 1 from natural enemies and from freezing, pointed 
to a distinct increase in the number of dead scales following the cold weather. In 
these studies it was observed that the body contents of adult female scales,which had 
died from natural causes or had been killed by parasites or predators were dried or 
eaten and their appearance was not changed by freezing. The scales recorded as 
frozen showed a collapsed body wall, oily appearance and discoloration, a condition 
distinctly different from that of the insects dead from other causes, and this condition 
indicated that before being frozen the body contents of the frozen scales were normal 
and these scales living. 
The records of the mortality from various causes were determined by counts of 
material taken from the same twigs at the same time, so that the gradual rise during 
the winter in the natural mortality does not influence the results. The number of 
scales recorded as killed by natural enemies after the drop in temperature was about 
2% less than the number dead from this cause during the four weeks preceding the 
cold. No consideration has been given to the influence on the counts of the dead 
scales which loosened and fell off as the study progressed and it is quite probable that 
many of the frozen scales were handicapped by a low vitality or an exposed position 
so that they would have succumbed naturally to the climatic changes of a more 
normal winter. 
The comparison is made of results of observations on the mortality of the camphor 
scale from January 22, 1924, 16 days after the freeze, at which time the insects had 
reacted to the cold sufficiently to give accurate information, to February 29, 1924, a 
total of 12 examinations. The examination of 5225 adult female scales at 12 semi¬ 
weekly intervals during this period, showed 2660 or 50.91% 2 dead. Of these 1576 
or 20.16% of the total number examined were recorded as killed by natural causes, 
840 or 16.08% by freezing, 138 or 2.64% by parasites, and 106 or 2.03% by predators. 
Observations during the four weeks previous to the low temperatures showed that 
1047 or 28.31% of the 3698 adult female scales examined were dead from natural 
causes and natural enemies. 
Records of the examination of 1859 female camphor scales, collected March 8, 
1924 on Citrui trifoliata growing below buds of Satsuma orange trees five miles south 
of Mobile, Alabama, where the minimum temperature is said to have ranged from 
10° F. to 14°F. on January 6, 1924, showed 1100 or 59.17% of the total scales dead. 
No decrease in the number of natural winter eggs per female has been apparent 
and in other respects fihe surviving over-wintering females appear normal. All live 
male scales had issued from beneath their coverings previous to the freeze. 
The data secured from examinations of the Florida Red Scale, Chrysomphalus 
aonidum (Linn), collected on camphor leaves at New Orleans, La. showed 40.08% 
of the adult female scales dead from natural causes and natural enemies during the 
] This term is used in this note to cover all causes of mortality other than 
insect parasites, predators and freezing. 
Calculation of two decimal places has been a routine practice in our studies. 
Special significance is not claimed here. 
