14 BULLETIN 730, U. S. DEPARTMENT OF AGRICULTURE. 



Geer, Myrmica punctiventris Roger, Lasius americanus Emery 

 Cremastogaster lineolata Say, and Solenopsis debilis Mayr. 



PARASITES. 



In August, 1916, it was found that many of the curculio eggs were 

 being destroyed by a minute hymenopterous parasite, determined 

 by Girault as Anaphoidea conotracheli Girault PL (II, G), a well- 

 known egg parasite of the plum curculio, Conotrachelus nenuphar 

 Herbst. This parasite is about half a millimeter in length and is 

 barely visible to the naked eye. The legs and bases of antennas are 

 light brown and the rest of the body is black. In 1917 this parasite 

 was again abundant and was observed frequently ovipositing in the 

 curculio egg punctures in grapes. When a fresh puncture was made 

 by the grape curculio several of these egg parasites would collect 

 about it and could be seen through a lens, thrusting their ovipositors 

 through the skin of the grape into the curculio eggs in the egg chamber. 

 Males usually were present and copulation would take place while 

 the females were struggling with one another for a desired position over 

 the egg chamber. Adult parasites issued in from 10 to 13 days after 

 their eggs had been deposited within the eggs of the grape curculio. 

 When the mature parasites leave the host eggs they sometimes enter 

 the pulp of the grape and mine through it to the surface, making a 

 threadlike burrow half an inch or more in length. The exit hole of 

 the parasite in the skin of the grape is usually near to the original 

 puncture of the curculio. 



In determining the extent of parasitization by this species, about 

 50 curculio beetles were confined on July 24, 1917, in a wire-screen 

 cage over a live branch of grapevine bearing 8 bunches of sound fruit. 

 Two days later the cage and curculios were removed and the punc- 

 tured grapes left exposed for six days to the attacks of the egg para- 

 sites. A later examination showed that 134 curculio eggs had been 

 deposited in the grapes and of these 53, or 39.5 per cent, had been 

 parasitized. The oviposition period of the curculio is sufficiently 

 long for the development of four or five successive generations of the 

 parasite. This may account for an apparently constant increase in 

 the percentage of parasitized curculio eggs as the season advances. 



Another parasite, Microbracon mellitor Say (PI. II, D) was ob- 

 served frequently ovipositing in infested grapes on the vine and on 

 the ground. The larva of this species attacks the larva of the curculio 

 externally and devours it, after which it constructs within the grape a 

 small, dirty-white cocoon from which the adult parasite escapes within 

 a few days. A third hymenopterous parasite, Stiboscopus brooJcsi 

 Ashm. (PI. II, E), attacks the curculio while within the cocoon. 

 This parasite is about 4 mm. in length, the ovipositor being one-third 

 as long as the body. The head and thorax are shining black, the 



