TWENTY-EIGHTH FRUIT-GROWEKS' CONVENTION. 



99 



cells do not heal and become discolored and badly spotted. Left on the 

 tree, they recover and no spots appear. This is a very important truth, 

 as it will urge the delay of picking, which will result in giving the 

 consumer much sweeter fruit and our California oranges a much better 

 reputation. Mr. Garstin also stated that the spotting had been observed 

 for two or three years; that it was first alarming last year, and that the 

 present year often as much as 10 per cent of the fruit was ruined. As 

 this spotted fruit was mixed with the other, it often led to rejection of 

 the. entire carload. 



On February 13th, Messrs. S. A. Pease and G. R. Holbrook, Horticul- 

 tural Commissioners of San Bernardino County, came to my laboratory 

 with more of the spotted oranges. Mr. Pease, whom I have always 

 found most cautious and accurate in all such work, also brought the 

 thrips, which I placed under a microscope and exhibited to the students 

 and the commissioners. Mr. Pease had closely observed the thrips at 

 work, had taken as many as fourteen from a single spot, and only found 

 the thrips on oranges, where the spotting was much in evidence. He 

 found this true: no spots, no thrips; much spotting, many thrips. I 

 have taken as many as thirty thrips from a single orange or lemon 

 blossom; Mr. Pease has taken even more. Mr. Pease is worthy of all 

 praise for the intelligent, energetic, untiring work that he has put into 

 this study. He has surely changed hypothesis to fact, and all this with 

 very little or no aid from other investigators. 



Why the Change. — Many wonder why spotting occurs now and did 

 not in the earlier years. This is no surprise to the entomologist. Insects 

 change their habits. Every year witnesses the black scale anchored on 

 new and different food plants. Again, insects often change from one 

 part of a plant to another, because of change in the plant. Many 

 species of Lecanium work when young on the leaves, but as the leaves 

 become dry from age or lack of sap, the young scale hie themselves to 

 the branches. Thrips usually work on leaves and blossoms and the 

 tender stems. It would not be strange if they, upon occasion, should 

 betake themselves to the fruit, and who could wonder that if one of our 

 magnificent Navels were once tasted it should hold the banqueter to 

 further feasts? It may be true that some condition of the tree, either 

 from weather or soil change, makes the leaves less juicy and palatable, 

 and thus the thrips in search of new and better pasture-ground betake 

 themselves to the fruit. The fact that spotting — thrips injury — is most 

 marked early in the season and disappears later would argue in favor 

 of this second view. 



Description of Thrips. — The thrips are very minute, so minute that 

 even good observers may fail to note their presence. The one in ques- 

 tion is only about one twenty-fifth of an inch in length. They are also 

 ubiquitous. Hardly a leaf or flower, twig or grass blade that does not 



