THE MONTHLY BULLETIN. 277 



NATURAL ENEMIES OF THE SUGAR BEET LEAF- 

 HOPPERS IN CALIFORNIA. 



By William J. Hartung and Henry H. P. Severin, Spreckels Agricultural 



Experiment Station. 



The losses sustained by the sugar beet growers and beet sugar factories 

 from the condition called "curly-top" or "curly-leaf," which has peri- 

 odically made its appearance since the introduction of the sugar beet 

 in the southwestern states, have reached many millions of dollars. It 

 has ])een estimated that the sugar cane leaf hopper (PerkinsieUa saccha- 

 ricida Kirk.) caused a loss of $3,000,000 to the planters of the Hawaiian 

 Islands during 1903 and 1004. After the introduction of the sugar cane 

 ]('afhoppcr many natural enemies already present in Hawaii transferred 

 their attacks to this pest, but it was not until after special introduc- 

 tions of parasitic insects that the hopper was brouglit under complete 

 sub.jection. In this paper wc shall discuss the natural enemies of leaf- 

 hoppers of the sugar beet in California, and in a future paper the possi- 

 bility of controlling the sugar beet leafhopper (Eutcttix tenella Baker) 

 by introducing parasites. It must be noted, however, that Perkinsiella 

 sac ch arid da and Euteifi.r tcnvUa are by no means closely related; the 

 former belongs to the family Fulgorid:r and the latter to the Jassidae. 



In order to secure data on the percentage of leafhoppers that were 

 parasitized, the specimens M'ere usually collected at random by sweeping 

 beet leaves with an insect net. The hoppers captured were taken into 

 the laboratory and placed either in breeding jars or vials. The bottoms 

 of the breeding jars were covered with filter paper on which was placed 

 a few beet leaves and stems to serve as food material, while the top of 

 the jars was covered with bolting silk. In each vial four Jassids were 

 confined together with a piece of beet leaf stem, and then the vials 

 were plugged with cotton. 



On September 2, 1913, 500 leafhoppers were captured by sweeping 

 with an insect net in the sugar beet fields at King City, California. 

 The beet leaves showed a severe condition of "curly-top." During the 

 following three weeks 12 puparia of a Dipterous parasite and also 

 12 dead hoppers were found at the bottom of the breeding jars or vials. 

 When the Dipterous larva issues from its host, it escapes by rupturing 

 the abdominal segments, near the junction of the metathorax. Four 

 Jassids showed the presence of a larval sac of a Dryinid beneath one 

 or the other wing. After the parasitic larva quits its prey, it spins a 

 white cocoon (length 3 mm., width 1.5 mm.) on the beet leaves. Each 

 dryinized hopper died after the emergence of the larva. In the season 

 of 1913 at least 3.2 per cent of the beet hoppers were parasitized, but it 

 must be noted that many of the pests died in confinement and, there- 

 fore, our record on the percentage of parasitism is not correct. 



The Dipterous parasites emerged after remaining in the pupal stage 

 for a period of 22 days. On October 24th, forty days after spinning 

 its cocoon, a wingless, ant-like parasite of the family Dryinidie issued. 



The Dipterous parasites were sent to Mr. P. Knab, of the U. S. 

 National Museum, for identification. He writes: "It very quickly 

 developed that there were two species, both of which are new; or 



