Nov. 15, 1920 Life History and Habits of the Beet Leaf hop per 251 



no further developed than the third instar. In all instances, however, 

 where an action thought to be oviposition was observed, the adult host 

 was the victim. 



The adult is very graceful in flight, darting here and there so suddenly 

 that it is impossible to follow the movements with the eye. The beet 

 leaf hopper, also, is very quick in its movements, but none is quick enough 

 to avoid this active little parasite. 



Pipunculus vagabundus Knab. — This species is not common in the 

 Salinas Valley and is of little importance. Its habits are similar to those 

 of Pipunculus industrius, and, with the exception of the conspicuous 

 stigma which is absent in the wings of P. vagabundus, the two species 

 are similar in appearance. 



Dryinidae. — Occasionally beet leafhoppers, both adults and nymphs, 

 are found with a dark brown sac or pouch protruding from the abdomen 

 (Pi. 42, D). This pouch contains the larva of a dryinid parasite. Har- 

 tung and Severin (6) report a parasite of this family, Gonatopus contort- 

 ulus Patton, from the Salinas Valley. Although the writer has reared 

 many specimens of this family, none has been determined. Judging from 

 the number of parasitized leafhoppers collected, these dryinids are not 

 of much economic importance. It has been observed, however, that the 

 adults devour a larger number of the leafhoppers, especially nymphs, 

 than they parasitize. In this way they may be of more importance than 

 would at first appear. 



SUMMARY 



Eggs of Eutcttix tcnella are deposited in a wide range of cultivated and 

 wild plants, but the sugar beet seems to be preferred for this purpose 

 during the summer season. A maximum record of 247 eggs was obtained 

 for a single female. The incubation period covered from 10 to 15 days 

 during the height of the egg-laying season and the nymphal period from 

 25 to 52 days. 



One generation only was observed in southern Idaho, while from two 

 to four were observed under California conditions. 



In southern Idaho the beet leafhopper appears in the beet fields in 

 June and starts reproducing at once, oviposition continuing throughout 

 the season. After harvest the leafhoppers enter a true hibernation pe- 

 riod. 



In California the adults appear in the beet fields soon after April 1 and 

 remain until harvest time, when they disperse to wild vegetation suitable 

 for food and protection. No true hibernation was noted in California. 



Three species of egg parasites were reared and studied. Two of these 

 are very effective. Two species of Pipunculus, internal parasites of the 

 nymphs and adults, were reared; and one of these was quite effective. 

 Dryinid parasites, also, were reared but are not considered very efficient. 



