1, THE FLORIDA ENTOMOLOGIST 
sixths of the aphids on a tree the one-sixth left will have repro- 
duced the original number in twenty-four hours, leaving out of 
consideration the number eaten by predators meanwhile. Of 
course, he has given the aphids more than a twenty-four-hour 
setback because several days must elapse before the young 
aphids can start breeding. But if he can kill 95% of the aphids 
the predators can be depended on to make some impression on 
the remainder. 
The two methods of control which have been most uniformly 
successful under most weather conditions are dipping and dust- 
ing under tents or fumigation. 
Dipping is applicable only to young trees, up to two or three 
years, and then only when the new growth is mostly out on the 
ends of the branches where it can easily be bent over into a 
bucket. Effective and perfectly safe dips are a solution of 
“derris oil,” a tablespoonful to a gallon of water, or the same 
amount of nicotine sulphate plus an ounce or less of soap. If too 
much soap is used burning may result. 
Dusting under tents has been very effective and practical, and 
an average kill of 99.7% has been obtained. A crew of three 
men with a battery of from six to ten tents can fumigate an acre 
an hour if the trees are not over 9 or 10 feet high. Using 3 per- 
cent nicotine sulphate lime dust, trees averaging 7 feet in height. 
cost 8 mills per tree for dust, less than a cent. The saving of 
dust on young trees, as compared with dusting in the open, 
almost compensates for the increase in labor cost, and the per- 
centage of kill is much higher. Different types of tents have 
been designed to accommedate different sized trees. For trees 
less than a year old, sheeting stretched over a framework made 
of telephone wire has been satisfactory. A vegetable hamper 
covered with sheeting would answer. For trees up to a height 
of five feet, 6-foot “rabbit” wire fencing rolled into a cone makes 
a satisfactory framework. These tents are set over a tree, which 
is then dusted throu a hole in the tent. For larger trees, up to 
9 feet, a tent made in the form of half a cone, with a framework 
of 54-inch gas pipe, has been found most satisfactory. It does 
not have to be lifted over a tree, only set up against it. A sheet 
of cloth with one side only sewed to the framework serves as a 
flap to close the open end after the tree is dusted. For larger 
trees tents made after the model of those used in California are 
best. For smaller trees tents made in the form of a bag stiffened 
