360 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[\'0l. S 



in premature falling of the flower before setting of the fruit. In the 

 Santa Clara Valley I have examined peach blossoms which contained 

 a great number of thrips and even before the fruit had had a chance to 

 set the damage was so serious that by gently stripping my hand down 

 a twig nearly every blossom would fall. The almonds, the first crop 

 to blossom, are damaged to a slight extent where the thrips occur 

 in numbers, but the prunes, plums, peaches, apricots and cherries, 

 which follow in rapid succession, are the fruits which are damaged the 

 most. This had been an unusual spring (1913) for thrips and they 

 have done serious damage to crops in the Santa Clara Valley. One 

 orchardist estimated that nearly two-thirds of the ''set'" on his peach 

 orchard was destroyed by thrips this j^ear. These trees are commonly 

 infested with Euthrips pyri. Euthrips occidentalis, Eufhrips tritici, 

 and Oelothrips kuwanaii, though Euthrips pyri occurs in much the 

 greater numbers. 



Damage to Alfalfa Grown for Seed 



On alfalfa I have collected quantities of Euthrips tritici and Euthrips 

 occidentalis. Though alfalfa is not grown for seed in the Santa Clara 

 Vallej^, I have had a chance to observe the work of the thrips, as the 

 insects occur in considerable numbers there. The damage here is 

 much the same as in the flowers of the deciduous fruits. The j^oung 

 floral parts are attacked, and the damage results in the premature 

 falling of the flower or the young seed pod. Though the oyslyj is 

 very pubescent 1 have observed thrips feeding about the base and also 

 along the tender stigma. Often I have found specimens of alfalfa 

 where nearty all the small pods had dropped from the main stem and 

 only a few remained near the tip. Where this damage could not be 

 directly traced to the feeding of Diabrotica soror, and the thrips were 

 present in great numbers, the damage was most likely the result of 

 thrips attack. 



Bibliography 



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 Zool. 47 Bd.). 



1890. Garman, H. The Mouthparts of the Thysanoptera (Bulletin Essex Insti- 



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1891. BoHLS, J. Die Mundwerkzeuge der Physapoden (Dissert. Gottingen). 



1895. UzEL, H. ]\lonographie der Ordnung Thysanoptera. 



1896. Garman, H. The Asymmetrs' of the ^Mouthparts of the Thysanoptera 



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 1899. BuFFA, PiETRO. Coutributo alio studia anatomico della Heliothrips hse- 



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