14 



THE TOBACCO THRIPS. 



less than in 1904 must have been due to the greater precipitation. 

 As before stated, it is quite evident that the amount of injury by 

 thrips will vary from year to year, depending upon the period and 

 amount of rainfall. The total precipitation in inches at Tallahassee, 

 Fla., during April, May, June, and July of the years 1898-1906 is 

 shown in the following table : 



Precipitation in inches at Tallahassee. 





April. 



May. 



June. 



July. 



Length of 

 record 

 (years). 



Year. 



Total. 



Depar- 

 ture from 

 normal. 



Total. 



Depar- 

 ture from 

 normal. 



Total. 



Depar- 

 ture from 

 normal. 



Total. 



Depar- 

 ture from 

 normal. 



1898 



1899 



0.87 



-1.89 



1.55 



-2.65 



4.49 



- 1.25 



10.00 



+ 1.71 



14 



1900 



1901 



1902 



1903 



1904 



1905 



1906 



4.05 

 2.72 

 0.84 

 0.11 

 1.65 

 0.92 

 0.15 



+1.05 

 -0.27 



-1.15 , 

 -1.88 

 -0.34 

 -1.07 



-2.43 







2.06 

 5. 07 

 2.86 

 5. .^9 

 1.05 

 7. 55 

 2.92 



-1.60 

 +1.59 

 -0.62 

 +2.11 

 -2. 43 

 + 4.07 

 + 0.70 



16.47 

 5.61 

 9.94 



10.01 

 1.33 

 3.50 

 5.17 



+ 10.72 



- 0.75 

 + 3.58 

 + 3.65 



- 5.03 



- 2.86 



- 1.23 



10.31 

 8.25 

 5.83 

 7.09 

 3.95 

 8.76 

 8.88 



+1.87 

 +0.02 

 -2.40 

 -1.14 

 -4.28 

 +0.53 

 -hi. 00 



15 

 16 

 17 

 18 

 19 

 20 

 21 







Insects. — Specimens of a small bug, Triphleps insidiosus Say. 

 were found very commonly upon oats, where they seemed to be quite 

 destructive to the thrips. When captured with the thrips by sweep- 

 ing the oats with a net, they were shortly found with a thrips im- 

 paled upon their beaks, sucking out the juices. While this insect 

 may assist in decreasing the tobacco thrips that breed on oats, it has 

 not as yet been found on tobacco. 



A fungus also was found growing upon dead thrips taken from 

 tobacco in the seed bed: but this may be, and probably is, a form 

 attacking- the insect after its natural death. 



REMEDIES. 



Remedies may be considered under two heads, namely, cultural 

 methods and insecticide applications. 



CULTURAL METHODS. 



It is the practice of many tobacco growers to start the seed bed in 

 the shade-tobacco field (see PL II), and, after the plants are removed, 

 to plant it with the rest of the field. This practice is unquestionably 

 a bad one, not alone from its furnishing a breeding place for the 

 thrips, but also because it becomes a center of infestation for many 

 other pests, particularly flea -beetles. It was noticed during the sum- 

 mer of 1905 that insect pests, and especially flea-beetles, were the most 

 numerous in transplanted seed beds and in that part of the field 

 adjoining the seed bed. It seems advisable, therefore, that the seed 

 bed be located outside and at some distance from the tobacco field. 

 Where it is necessary that the seed bed be located in the field, the 

 thrips can be largely overcome by frequent applications of kerosene 

 emulsion, as hereinafter described. Applications of Paris green also 



