6 BULLETIN 616, U. S. DEPARTMENT OF AGRICULTURE. 



boxes, of navel oranges were shipped. The loss suffered from grade 

 reduction due to thrips by the Lindsay district alone, and in a season 

 of comparatively light infestation, was therefore about as follows: 

 Forty-three per cent, or 255,742 boxes, reduced to second grade at a 

 loss of 37 cents per box, making $94,624.54; and 23 per cent reduced 

 to third grade at a loss of 65 cents per box, making an additional 

 $88,914.80, or a total loss of $183,539.34. 



EXTENT OF DAMAGE IN SOUTHERN CALIFORNIA. 



It is calculated that from 20 to 40 per cent of the 1910 orange crop 

 of Eiverside County was sufficiently marked to keep it out of first 

 grade. The injury was most severe in groves in the hills to the south 

 and east of Riverside and in the vicinity of Highgrove, where con- 

 ditions are similar to those along the foothills in the San Joaquin 

 Valley. In this section about 55 per cent of the crop was lowered in 

 grade because of thrips marking. Of the 1911 crop in the same 

 groves, however, only 16.9 per cent was marked sufficiently to throw 

 it out of the first grade. 



At Redlands the injury was somewhat less severe than at River- 

 side. Only from 2 to 5 per cent of the first-grade fruit running in 

 the packing houses was marked, and that slightly, while from 50 to 

 60 per cent of the second-grade fruit was more seriously damaged. 

 The writer was informed that fruit from some of the groves was 

 injured more severely than that then passing, and when such fruit 

 was being packed an additional or third grade was added to accom- 

 modate the thrips-marked oranges. 



In the Pomona- Claremont-Upland section damage by the citrus 

 thrips was much less severe than at Riverside and Redlands. The 

 grades of fruit then running were " fancy " and " choice," and it was 

 estimated that about 10 per cent of the first-grade oranges had traces 

 of marking and about an equal percentage of the second, or choice, 

 fruit was more conspicuously marked. The most severe marking oc- 

 curred at Claremont, which is nearer the hills, a little warmer, and 

 produces very vigorous trees. First-grade fruit was scarred about 

 equal to that at Pomona, but a third grade was run at Claremont, 

 about 25 per cent of which had been reduced because of thrips 

 scabbing. 



The injury decreases toward the coast, so that at Whittier only 

 about 10 per cent of the entire crop was scabbed. About 2 per cent 

 of the first and 5 per cent of the second-grade fruit had been slightly 

 marked. Less than 1 per cent of the marked fruit of second grade 

 would be placed in that grade because of thrips injury alone. Lemons 

 were blemished about as much as oranges. At Pasadena 90 per cent 

 of the 2,000 oranges examined in the field was entirely free from 



