oy 
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‘Florida Entomologist 
cee. (hee of the Florida Entomologicas JA 
vO. VIL. SUMMER NUMBER Not 
JULY, 1923 
IS THE ADULT CONDITION OF AN APHID DETERMINED 
WHEN IT IS BORN?* 
ARTHUR C. MASON 
Most aphids which are eventually to develop wings will, upon 
close examination, show wing pads, especially when approaching 
maturity. On some species these show distinctly, but on others not 
so plainly. Usually they are not very noticeable until the last 
instar preceding maturity. The question now arose as to whether 
the adult form of the aphids was determined when it was born. 
Was it possible to prevent, under favorable conditions, an aphid 
which had wing pads from developing wings, or to cause, through 
unfavorable conditions, an aphid without pads to develop wings? 
To determine this point some experiments were planned. 
Twelve specimens of Lachnus pini in the first instar and show- 
ing wing pads were placed on a pine branch in a cage on the tree 
and allowed to mature. Also twelve specimens not showing wing 
pads were placed in a second cage. Of the first group all de. 
veloped wings, while in the second lot there were both winged 
and apterous forms. A probable error in this work lies in the 
fact that it is not possible to tell exactly if a small aphid has pads 
and consequently some of this lot undoubtedly had pads while 
in the other lot only those were selected which plainly showed 
wing pads. This experiment was repeated the same way on cut 
branches of pine under bell jars in the laboratory. The results 
were similar to those of the preceding experiment, all of the first 
group developing wings while the second had both winged and 
apterous forms. The same probable error occurs here also. 
A similar experiment was next tried with Myzus persicae. In 
this species however it is much harder to distinguish those hav- 
Peontinued from Vole Vil, No. 25ep. 32: 
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