iUMMARY OF INSECT CONDITIONS DURING 1921. 



37 



Data on the departures from normal temperature and rainfall in 

 1920-21 in the region infested by the sweet-potato weevil are given 

 in Figure 19 and in Table 9. 



Table 9. — Monthly departures from normal temperature and rainfall from 

 September, 1920, to September, 1921, inclusive, in the region infested by the 

 sweet-potato weevil. 



DEPARTURES (IN DEGREES FAHRENHEIT) FROM NORMAL TEMPERATURE. 





1920 



1921 





Sept. Oct. Nov. Dec. Jan. Feb. Mar. Apr. 



May. June. July. 



Aug. 



Sept. 



Texas 



Louisiana 



Mississippi 



Alabama 



Georgia 



Florida 



....+1.8 +0.5 -2.9 +0.5 +5.7 +3.6 +5.6 -1.8 

 ....+2.5 +.5 -4.2 +.4 +5.8 +-4,3 I+-7.8 -1.2 



....-2.6 +1.0 -4.2 -.1 ^-5.1 +4.2 +S. 4 -1.3 

 ....+1.7 +.4 -2.9 -1.0 +4.1 +3.4+7.7 -.8 

 ....-1.5 -.2 -1.6 +.2 +3.1 +3.9+7.7 +.2 

 .... +.6 -1.8 -1.1 -.8 +2.0 +3.0 +5.4 +.4 



+0.6 -0.8 +0.0 



-.8 , +.2 +.8 

 -.4 +1.9 +1.7 

 -.7 +2.9 +1.5 

 -1.9 +2.0 -.2 

 +2.2 +.7 -.7 



+ 1.7 

 + 1.7 

 + 1.9 

 +.9 



+ .3 



+4.0* 

 +4.2 

 +5.9- 

 +6.2 

 +6.2 

 +2.7 



Regional mean 



....+1.8 +.1 -2.8 -.1 +4.3 +3.7+7.1 -.7 



1 I i 



-.1 +1.1 +.5 



+ 1.0 



+4.8- 





DEPARTURES (IN INCHES) FROM NORMAL 



RAINFALL. 







Texas -0. 65 +1. 20 -0. 27 -0. 66 +0. 04 -0. 29 +0. 82 +0. 46 -1. 74 +3. 39 -0. 42 -1. 60 +1. 20- 



Louisiana -.02 -.20 -.55-4.10-1.27-2.28+1.35+1.77-1.54 +.55 +.35 -2. OS -.74 



Mississippi -.19-1.21 -.02+3.11-2.00 -.66+2.64+4.09-3.00-1.43 — . 51 — . 66 -.33 



Alabama -.71-1.54 -.07-2.92-1.65 +.04 -.94+2.05-1.96-2.18 -.34; +.48 +.76 



Georgia -.05-1.87+1.12+1.31 -.96 -.54-3.21 -.22 +.72-2.00+1. 13 -.95-1.44 



Florida -1. 32 -2. 75 +1. S3 -. 63 -1. 49 -1. 56 -1. 16 -. 58 +1. 95 -2. 74-1. 43 -2.32 -4. 52 



Regionalmean -.03 -.99 +.63+1.90-1.22-1.04 -.08+1.26 -.93 -.73 +.25-1.02 -.86 



POTATO LEAFHOPPER. 



(Empoasca malt LeB.) 



During the year the potato leafhopper was seriously destructive 

 over a large part of the commercial potato-growing region of the 

 United States, and Mr. Gibson. Dominion entomologist, reports 

 it as the most destructive potato pest during this season in Canada. 

 The association of this insect with potato tipburn (" hopperburn ") 

 has stimulated interest in the depredations of this pest. Part of 

 the distribution areas on the accompanying map (Fig. 20) were ob- 

 tained from the survey reports of the plant disease survey. Bureau 

 of Plant Industry. 



The most serious infestations were in the North-Central and East- 

 Central States. In Illinois the leafhopper caused considerable loss 

 to potatoes over the entire State, except where these were protected 

 by Bordeaux spray. Serious injuries were also reported from the 

 northern half of Indiana and the central part of Ohio. The insect 

 was also seriously abundant throughout the entire potato growing 

 sections of Minnesota. Wisconsin, and Michigan. 



In North Dakota outbreaks were recorded from the southeastern 

 part of the State, extending from Grand Forks Count v to Dicker 



