26 THE FLORIDA ENTOMOLOGIST 
Species Used. For carrying on these experiments the follow- 
ing three species of aphids were mostly used: Lachnus pini L., 
Myzus persicae Sulz., and Aphis gossypu Glov. These aphids 
could be found in greater or less abundance at all times of the 
year and both winged and apterous forms occurred naturally in 
the colonies. They continued to reproduce viviparously all 
through the winter and hence a supply of adults could always be 
obtained. The last two species lived on a number of different 
host plants and so could be raised under varying conditions. 
Another species, Macrosiphum davisi, had been observed for a 
year on the rose bushes and no winged forms ever occurred. 
Hence some work was done to try to produce some individuals 
with wings. 
EFFECT OF INJURY TO HOST PLANTS 
Starting out with what appeared to be the most promising 
methods of securing results, some experiments were run to 
determine the effect of injury of the host plant on the aphids. 
For this work some small pine trees infested with Lachnus pini 
were selected. The object was to injure the branches by girdling 
or partial girdling so as to shut off the flow of sap in the branch 
and determine the effect on the aphids. 
Branch A was injured by cutting the bark and cambium layer 
for one-third of the distance around it; branch B had the bark 
cut through the cambium layer for two-thirds of the distance 
around; branch C was a check, uninjured. On each of these 
branches was placed a small colony of Lachnus pini in a cage. 
Another small tree was completely girdled around the base and 
a colony placed on it in a manner similar to the others. This 
colony is designated as D. A third tree was uninjured and a 
colony placed on it for a check, designated as E. These experi- 
ments were begun in November and were run for about two 
months, the results being recorded two or three times a week. 
The number of winged forms found each time were counted and 
the results tabulated.” The table shows that winged forms were 
produced in all the cages. On the first tree check colony C had 
approximately as many winged forms as colonies A and B which 
were on injured branches. Colony D also had a large number of 
winged forms but check colony E for a few weeks produced only 
apterous forms. Later on, however, winged ones appeared. 
°The tables are necessarily omitted because of lack of space and instead the 
results are summarized. The photographs illustrating the work are also excluded. 
