LIBKAKY 
STATE PLANT BOARD 
ET-172 December 1940 
United States Dstartinent of Agriculture 
Bureau of Entomology and Plant Quarantine 
PERCENTAGE TABLES 
FOR NUMBERS FROM 1 TO 250 
By Charles A. Clark, 
Division of Cereal and Forage Insect Investigations 
INTRODUCTION 
Percentage tables similar to those made available in this 
publication have been used for several seasons at the entomological 
laboratories engaged in the study of the European corn borer in the 
United States. The tables have been found very useful in a number 
of different phases of the research program on the corn borer, and, 
with the hope that they will prove useful to many research workers 
in various fields of investigation, it seems worth while to make 
them generally available. They have been carefully checked, and 
it is believed that their use will reduce calculation errors. 
The use of these tables is quite simple, and the following 
example will suffice to show how they should be used. 
Parasitization studies: Many collections of host insects 
have been made to obtain data on parasites and parasitization. One 
of these collections contained 137 host insects and three species 
of solitary parasites were reared therefrom. Ten adults of para- 
site A, 18 of parasite B, and 15 of parasite C, or a total of 43 
parasites were recovered from the 137 host insects, and it is de- 
sired to know the percentage of parasitization by each parasite as 
well as by the parasite complsx as a whole. Turning to the column 
137 (the number of host insects in the collection) on page 25 of 
the tables, we may read the percentage of parasitization for each 
parasite at the point where the horizontal line opposite the proper 
figure for the number of parasites reared intersects the 137 column, 
thus : 
Parasite A number reared 10 percent parasitization 7.3 
n b " " 18 " " 13.1 
C " i 15 " » 10.9 
A, B, and C " " 43 " " 31.4 
