2 | THE FLORIDA ENTOMOLOGIST 
ing pads from those without them, until just before the last molt. 
However, some attempts were made to select some without and 
try to produce wings on them. Twelve immature specimens were 
placed on each of four cuttings of orange tips in sand. A and B 
were watered with a 3% magnesium sulphate solution, and C and 
D were watered with distilled water. The results showed both 
winged and apterous forms developed with a majority of winged 
in all cases. The number in the two checks was about equal to 
the number in the treated jars. A second trial using only one 
individual on each cutting produced similar results. Those on 
stems in magnesium sulphate solution were all apterous and 
those in water were half winged and half apterous. Four checks ~ 
tied up on a limb of an orange tree resulted in three winged and 
one apterous. On these results it is probable that the cause of 
wing production was due to wrong selection of aphids rather 
than to a change of conditions. The checks also produced wings. 
It is practically impossible to select aphids of this species, when 
young which we can tell with certainty will not develop wing 
pads. 
One more experiment was run on aphids of this species whose 
lineage was known. Four specimens of Myzus persicae were 
selected from the lines used in the life history work. Their 
parents had been apterous for four generations back. They were 
all kept on a cabbage plant until eight days old and then two of 
them, C and D, removed each to a separate orange tip in sand 
and watered with distilled water. The other two, A and B, were 
left on the plants for checks. All matured apterous. A and B 
together then raised 17 young on the cabbage plant of which six- 
teen were apterous and one winged. C on orange tip raised five 
young, all apterous. D on orange tip raised five young, four ap- 
terous and one winged. In the third generation raised from C 
and D there were together forty-six apterous and five winged 
aphids. Hence it is seen that even in the second and third gen- 
erations the number of winged forms on the cut stems is not 
increased over those on plants growing naturally. 
ALTERNATION OF WINGED AND APTEROUS GENERATIONS 
The question arose as to the possibility of there being an alter- 
nation of one winged generation with one or more apterous gen- 
erations. To investigate this point some colonies of the pine aphids 
were started on a small pine tree. Four winged adults reared a 
family the majority of which were apterous and four apterous 
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