December, '10] PIERCE: weevil parasitism 453- 



Cerambycobius sp., Eurytoma tylodermatis Ashmead and Micro- 

 dontomerus anthonomi Crawford are normally primary ectoparasites, 

 attacking weevils which do not enter the ground, their attack being 

 fatal in a very short time. Sigalphus zygobaridis Crawford attack- 

 ing Zygobaris xanthoxyli Pierce, Sigalphus curculionis Herbst attack- 

 ing Conotrachelus sp., and probably Eutrichosoma albipes Crawford 

 attacking Auleutes tenuipes Dietz and Smicronyx tychoides LeConte, 

 are normally primary ectoparasites, attacking weevils which enter 

 the ground for pupation, and do not kill the host until it has formed 

 its earthen cell. 



Averted simple ectoparasitism : Sometimes it happens that two 

 different kinds of insects live in the same plant in a similar manner 

 as Anthonomus squamosns LeConte and the fly, Rhagoletis grindelice 

 Coquillett, in heads of Grindelia squarrosa nuda. An instance of 

 averted parasitism occurred in the attack of this fly by Eurytoma tylo- 

 dermatis. 



Simple endoparasitism is not very common on the weevils which 

 have been studied. The solitary hidden eggs of most weevils do not 

 invite extensive parasitic attack; however, Girault has recorded 

 Anaphoidea conotracheli Girault from eggs of Conotrachelus nenuphar 

 Herbst, and A. sordida Girault from eggs of Tyloderma foveolatum 

 Say. The larvae are more frequently attacked. Among weevil para- 

 sites endoparasitism is displayed by Myiophasia cenea Wiedemann, 

 Ennyomma globosa Townsend in the Tachinidge, and by Tetrastichus 

 hunteri Crawford in the Chalcidoidea, all attacking the boll weevil. 

 Weevils of the genus Conotrachelus are attacked by Cholomyia 

 incequipes Bigot, Metadexia basalis Giglio-Tos, and Myiophasia cenea 

 Wiedemann. The latter parasites are therefore forced to dig their 

 way to the surface of the ground. 



Multiple endoparasitism is probably the result of polyembryony 

 in the following cases which are the only instances of multiple para- 

 sites of weevils known perfectly to us; viz., Horismenus lixivorus 

 Crawford attacking Lixus scrobicollis Boheman, and an undescribed 

 Tetrastichus attacking Orthoris crotchii LeConte. The number of 

 Horismenus bred from a single host was very variable, being some- 

 times as high as 47. In both cases the parasites are internal and leave 

 the host to pupate. 



True hyperparasitism is at present unknown in the studies of 

 weevil parasites. 



Non-fatal superparasitism will be seen by the examples rendered 

 to be much less common than the fatal. It displays several very 

 peculiar phenomena. 



