38 



PEELIMIXARY REPORT OX ALFALFA WEEVIL. 



OTHER PARASITES. 



The following three parasites came mainly in the last two shipments 

 from Italy. The adult of one species (Canidiella curculionis Thorns.) 

 (fig. 25) oviposits in the larvae of the alfalfa weevil in different stages 

 of development, but the offspring therefrom 



emerge from the 

 cocoon spun by the 

 weevil, the cocoons 

 of the parasite always 

 showing through the 

 meshes of the cocoon 

 of the weevil (see fig. 

 27). This species has 

 two generations an- 

 nually and hibernates 

 as cocooned larvae. 

 The alfalfa stems 

 from which the three 

 species of parasites 

 of this group were 

 reared were also in- 

 fested by Apion pisi Fab., and therefore some or all of the group may 

 perhaps also parasitize this latter insect. Owing to its small size, 

 however, as compared to the parasites, this seems rather unlikely. 

 The two additional species reared with the preceding 



are not definitely determinable, but 

 one is PJiygadeuon sp., and the 

 other may prove to be Mesochorus 

 nigripes Ratz. Of this latter spe- 

 cies Mr. T. W. Wassiljew, a Russian 

 entomologist, under date of Febru- 

 ary 6, 191*1, wrote us: 



Fig. 21.— Pteromalicl parasite of larva 

 and pupa of the alfalfa weevil: a, 

 Enlarged pupa of alfalfa weevil with 

 eggs of parasite in place; b, egg, 

 greatly enlarged. (Original.) 



Fig. 22.— Pteromalid parasite 

 of larva and pupa of the 

 alfalfa weevil: Larva. 

 Greatly enlarged. (Orig- 

 inal.) 



I wish to say that I am able to give you 

 only one instance of a parasite having been 

 found, and that was in the vicinity of Tasch- 

 kent (Turkestan), where I noticed in the 

 past year [1910] thai over 20 per cent of the 

 larva? of P. variabilis were attacked by an 

 Ichneumon parasite. Unfortunately I do 

 not know the name of this species of para- 

 site at the present time, other than that it be- 

 longs to the Ichneumonidse. Judging from 

 the elliptical, thick-shelled cocoon it might 



possibly have been Mesochorus nigripes Ratz., which Mr. Ratzeburg (The Ichneu- 



monidae, III, p. 120) gives as a parasite of P. rumicus. 



All of these parasites resemble each other to a certain degree, and 

 figure 25 will suffice to illustrate them, for the present at least. At 

 the present stage of this experiment in introducing parasites of the 



Fig. 23.— Larva of ptero- 

 malid parasite attack- 

 ing pupa of alfalfa 

 w e e v i 1 . Enlarged. 

 (Original.) 



Fig. 24.— Pupa of 

 pteromalid para- 

 site shown in fig- 

 ures 22 and 23. 

 Greatly enlarged. 

 (Original.) 



