250 Journal of Agricultural Research vol. xx, No. 4 



NATURAL ENEMIES 

 EGG PARASITES 



The following three species of egg parasites have been reared from the 

 beet leafhopper and studied to some extent. They are given in the order 

 of their importance. 



Polynema EUTETTixi GiraulT (4, p. 18) (Pl. 43, A). — This small 

 brown or black species was first reared from eggs of Eutettix tenella at 

 Spreckels, Calif., early in 1915 and has proved to be the most effective 

 parasite of this group in the Salinas Valley. Eggs parasitized by this 

 species are conspicuous in the petioles of the beets because of the black 

 color of the parasite pupae. Development is rapid, the life cycle from 

 adult to adult covering about 35 days on an average, and there are at 

 least nine generations annually. 



Abbella subflava Girault. — Concerning this parasite W. J. Hartung 

 (5) writes as follows: 



Hyper-parasites were bred from parasitized eggs of Eutettix. These were deter- 

 mined by Girault as Abbella subflava Girault. 



This species 1 was never found among the parasites reared from ma- 

 terial collected at Spreckels, Calif., but at Riverside it w 7 as reared in 

 about equal numbers with Polynema eutettixi. 1 It is a primary parasite, 

 ovipositing readily in eggs of the beet leafhopper. It has also been 

 reared from eggs of Empoasca sp. 



Anagrus giraulti Crawford. — This common orange or red jassid 

 egg parasite has been reared in each locality where parasite studies have 

 been conducted. It oviposits readily in eggs of the beet leafhopper and 

 is usually reared along with Polynema eutettixi, but not in such large 

 numbers. The presence of this species in the petioles of the beet can be 

 detected by the red or orange color found in both larva and pupa. 



PARASITES OF THE NYMPHS AND ADULTS 



As previously reported by Hartung and Severin (6), two species of the 

 dipterous family Pipunculidae are known to be parasitic on the nymphs 

 and adults of the beet leafhopper. These have been described (7) as 

 Pipunculus industrius Knab and Pipunculus vagabundus Knab. The 

 former is the more common species in the Salinas Valley. 



Pipunculus industrius Knab (Pl. 43, B). — Eggs of this species are 

 deposited in both nymphs and adults of the beet leafhopper, but mature 

 larvae have never been know r n to emerge from a nymph. There are no 

 indications that the adult female prefers either the mature or immature 

 stages of the host in which to deposit her eggs, very small parasitic 

 larvse having been dissected in about equal numbers from both stages. 

 It is known, by dissection, that eggs may be deposited in small nymphs 



1 Specimens identified by Mr. A. B. Gahan. 



