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Florida Entomologist 
Official Organ of the Florida Entomological Society 
VOL. V SPRING NUMBER No. 2 4 
Ale, (1922 
LIFE HISTORY STUDIES OF SOME FLORIDA APHIDS: 
By ARTHUR C. MASON 
GENERAL 
It is a well-known fact that in the colder sections of the country 
the plant lice pass the winter in the egg stage. These eggs hatch 
in the spring into wingless agamic females. The process of pro- 
ducing apterous viviparous females usually continues throughout 
the season. Winged females sometimes appear, also, but in most 
cases only apterous forms are found. At the approach of cold 
weather the true sexual generations of both males and females 
appear. Fertilization takes place and the females lay eggs which 
live over winter to start the generation in the following spring. 
This, in general, is the mode of life of plant lice in the North. 
Experimental work has been done which tends to show that the 
true sexual forms are produced only when conditions are not 
favorable to the continued life of a species in the adult form. 
Slingerland (23)° of Cornell, raised 99 generations without pro- 
ducing a single sexual form in his insectary where conditions of 
heat, plant food, etc., were favorable to the aphids. Therefore, 
this might happen naturally under favorable conditions. From 
this experiment it is reasonable to believe that plant lice can live 
and breed viviparously over winter in Florida, and this phenome- 
non has actually been observed by the writer in the case of sev- 
eral species of aphids. No true males have been produced, nor 
have any sexual eggs been laid. Other workers also have offered 
this as an explanation of the life of southern aphids. Quaintance 
(82), in describing the life history of Aphis brassica says that 
1A synopsis of Part II of thesis entitled ‘‘Systematic and Biological Studies 
of Some of Florida Aphididae’ presented by the writer to the University of Florida 
in 1915 for the degree of Master of Science. This is the second paper of the series; 
the third and concluding paper will appear in a following issue. 
2 Numbers refer to references cited. Complete list of references for the three 
papers will appear at the end of the third paper. 
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