THE MONTHLY BULLETIN. 279 



From the data at hand 33.6 per cent of the leafhoppers were para- 

 sitized during the season of 1914, but we are not justified in drawing 

 any definite conclusions on account of the limited amount of material 

 collected at some localities and the fact that some of the specimens died 

 during confinement. 



In addition to these insect enemies a fungous disease was found to 

 attack the leafhoppers at King City. A hopper which contracted the 

 disease under field conditions was found on January 21, 1914, and on 

 the 27th of the same month a specimen still showing tracas of life with 

 the fungous growth was found. Unfortunately these diseased insects 

 were not kept and hence were not identified by a specialist. 



The reasons for the fiuctuatiou in number of the sugar beet leaf- 

 hopper may be due to complicated causes. An enormous increase of 

 Eutettix tenella may be followed by an undue nuiltiplication of para- 

 sites, followed l)y an increase of hyperparasites ; or in the absence of 

 hyperjKirasites, the primary parasites may perish due to scarcity of 

 leafhoppers during the following year, and the host, thus temporarily 

 free from their attack, is enabled to increase once more. Perkins 

 (2, pp. 14-15) has often observed how different species of Df\inid 

 parasites of leafhoppers are at times hard pressed by their hyper- 

 parasites. Perkins (3, pp. 127-128) bred a parasite of the family 

 Encyrtida^ from the puparium of Pipuncidus cinerascens. "The pupa- 

 rium of P. ci)ifras<'f)is being freely exposed on the surface of the leaves, 

 would naturally be liable to be attacked, and is probably stung at that 

 time." Up to the present time, w^e have bred no hyperparasitas from 

 the different species of Pipunculus or Gonatopus contortulus which 

 attack Eufctfix tcncUa. 



According to Ball (1, p. 36) the sugar beet leaf hopper is apparently 

 a native insect restricted to the lower levels of the mountain region of 

 the southwestern part of the United States. If this view is correct one 

 woidd l>e inclined to believe that the parasites have followed the pest 

 into the beet fields. On the other hand, these parasites may have trans- 

 ferred their attacks from closely related forms to Eutettix tenella. 

 Perkins' (2, j). 12) observations show that "in some cases a species of 

 the Dryinida^ will attack more than one species of leafhopper, and 

 indeed sometimes parasitizes species of different genera, yet in the 

 latter case these genera ahvays belong to the same group of hoppers. 

 In no ease have we ever found one to attack a Jassid or Fulgorid indis- 

 criminately." The PipunculidcC are known to affect various families of 

 Homoptera, the spittle insects or Cercopida:', the Fulgorida^ but on the 

 whole they appear to chiefiy parasitize the Jassidii^. "It is not known 

 whether in any case the same species of parasite will attack leafhoppers 

 of more than one family, e. g., Fulgorida3 and Jassida^." It is certain, 

 however, that some of these flies will attack very different si)ecies of 

 leafhoppers, often from two widely different genera of the same family. 



BIBLIOGRAPHY. 



1. Ball, E. D., 1909. Some Insects Injurious to Truck Crops. The Leafhoppers of 



the Sugar Beet and their Relation to the "Curly-leaf Condition." U. S. Dept. 

 Agr. Bur. Ent.. Bui. 66, pt. IV, pp. 1-52. 



2. Perkins, R. C. L.. 1905. Leaf-hoppers and their Natural Enemies (pt. I, Drymidas) 



Hawaiian Sugar Planters' Exp. ata., Div. Ent., Bui. 1, pt. I, pp. 3-69. 



3. , 1905. Leaf-hoDpers and their Natural Enemies (pt. IV, Pipunculidfe) Ibid., 



Bui. 1, pt. 4, pp. 123-157. 



•1. . 1906. Leaf-hoppers and their Natural Enemies (pt. X, Dryinidae, Pipun- 



culida;) Ibid., Bui. 1, pt. 10, pp. 483-499. 



5. , 1907. Parasites of Leaf-hoppers. Ibid., Bui. 4, pp. 5-66. 



6. , 1912. Parasites of the Family Dryinida;. Ibid., Bui. 11, pp. 5-20. 



7. Van Dine, D. L., 1911. The Sugar Cane Insects of Hawaii. U. S. Dept. Agr. Bur. 



Ent., Bui. 93, pp. 1-54. 



