DOSAGE REQUIREMENTS. 41 
all the immature white flies were in the pupal stage. Of the many 
thousands of specimens examined in the course of the experiments, 
less than five were in earlier stages. The principal experiments 
were conducted in the grove at the laboratory in Orlando. Fla., 
but cooperative experiments were conducted on a larger scale in an 
extensive grove in the western portion of Orange County. The 
detailed records concerning the efficiency of fumigation against 
the white fly refer to experiments conducted at Orlando. A group 
<>!* trees was selected for treatment on account of the comparative 
abundance of the live insects. As it was considered desirable to 
examine t ho insects both before and after treatment, leaves were 
selected at various distances from the ground, and in various sections 
of the tree, and the number of live and apparently normal pupae 
was aoted on a tag which was left attached to each leaf. After 
fumigation examinations were made at intervals of a lew days until 
the appearance of the pupae on the tagged leaves showed, beyond 
doubt, that the insects were dead or, if unaffected, • until the evidences 
of normal vitality were unmistakable or the adult insects had emerged. 
The acid used in the experiments, with the exception of experiments 
Nos. 45.37, 60.21 , X.7, and X.8, was tested with a Beaume hydrometer 
and found to be 66°, as guaranteed by the manufacturers. The 
potassium cyanid was guaranteed to be 99 per cent pure. A sample 
was analyzed in the Bureau of Chemistry of the Department of 
Agriculture and it was reported to contain 40.59 per cent cyanogen, 
a little more than 0.5 of 1 per cent more than that theoretically 
present in chemically pure potassium cyanid, the excess being due 
to a trace of sodium cyanid. 
As has been previously stated, the sheet tent used was made of the 
brand of S-ounce duck which is most used in California for fumigat- 
ing tents. The tent was untreated but was thoroughly shrunk by 
exposure to heavy dews and therefore as tight as those ordinarily 
used. 
A system of numbering the experiments was adopted which 
indicates the length of exposure and consecutive number of the tree 
treated for the particular duration of time. The number before the 
decimal point indicates this exposure for sixty minutes and less. 
Exposures ranging from one and a half to three hours are indicated by 
the letter X preceding the decimal point. 
'Fable IV summarizes the data based upon the experiments of 
January and February, 1907, concerning dosage for the white fly, 
including for convenience the dosage called for by the tables found in 
the appendix. 
