LIFE HISTORIES OF LEAFHOPPERS OF MAINE. 63 



of the beet (Eutettix tenella) which has been described in 

 detail by Dr. E. D. Ball. It seems the more likely since there 

 appears to be a decided tendency for the affected leaves to 

 change color and wither at the tips as well as around the punc- 

 tured spots and these effects differ from those of the plant lice 

 which are also suctorial and so far as withdrawing sap must 

 act very much like the hoppers. 



Inasmuch as the leafhoppers, plantlice and thrips are so com- 

 monly found associated even on the same plants a comparison 

 of the effect on the leaves may be useful. It may not be possi- 

 ble in every instance to say positively simply from the looks of 

 injured leaves without the finding of the insect concerned just 

 which one has been at work but from examination of a great 

 many leaves I believe that it is generally possible. Thrips injury 

 on the leaves show as minute dots or iines usually running par- 

 allel with the leaf veins and remaining white. If in the larval 

 stage they may be seen with a strong lens running actively 

 about on the leaf surface and some individuals will be found, 

 beneath the leaf sheath where their presence is likely to be in- 

 dicated by whitened spots. In the head they produce the blaster! 

 flowerets so well described by Dr. Hewitt. (Jour. Economic 

 Entomology Vol. 7, p. 211.) 



The plantlice which may be of two species as determined by 

 Dr. Patch (Macrosiphum granaria and Aphis avenae) cluster 

 mainly at or near the tips of the leaves or at the base of 

 the flowerets and travel much less freely than either the thrips 

 or the leafhoppers. Their results show in withering of the leaf 

 or floweret but without, for some time at least any particular 

 discoloration. The young leafhoppers on hatching usually 

 crawl out upon the leaf in which the eggs were deposited but 

 they drop or jump readily if disturbed and unless the leaves arc 

 examined with great care not to agitate them there is little 

 chance of finding them in connection with the spots which they 

 have produced. Moreover they seem to wander freely so that 

 numerous punctures will be found on leaves where there is no 

 other sign than the punctures that they have been present. The 

 character of the leaf spots made by their punctures may be in- 

 dicated by the photograph reproduced in Fig. 12. but unfortu- 



