424 IVAR TRÄGÅRDH [24] 



5. Other parasites of Lyda signata. 



Beside Trichogramma evanescens also other parasitic hymenoptera were ob- 

 tained during the outbreak of the saw-fly. The investigations were made 

 in the spring by digging in the ground where the larvse and pupae of the 

 saw-fly were hibernating. As the parasites of this species always leave their 

 hösts before pupating it is not strictly true that they were bred from the 

 saw-fly. But as they were found in the ground close together with larve and 

 pupae of the saw-fly and the forest consists of a pure spruce stånd, where no 

 other phytophagou insects occured there is every reason to believe them to 

 be the parasites of Lyda signata. The parasites were kindly identified by 

 dr. A. Roman of the Museum of Xatural History, Stockholm. They were as 

 follows: Xenosrhesis fulvipes Hgn.. Limnerium crassifemur Thn, Mesochorus syl- 

 varum Curtis and Holocremna nov. spec. The only one of these parasites, some 

 höst insects of which are known, is Mesochorus sylvarum Curtis, which has 

 been bred by Bignell from Vanessa atalanta, attacked by Microgasler sub- 

 complelus and by Lyle from Pandemis ribeana attacked by Pkytoduetus polo- 

 zonias. From these data it seems likely that Mesochorus is a hyperparasite. 



Beside the parasites which were bred from pupae and cocoons collected 

 in the ground the same species and others were caught in the forest. Ät 

 the end of July 1918 f. i. Xe?ioschesis fulvipes Hgn. was quite as abundant 

 in the forest as the saw-fly had been in the beginning of June. Amongst 

 these parasites Xenoschesis , Ilalocremna n. sp. and Mesochorus sylvarum occurred 

 beside the following species: Epiurus s/enostigma Thn, Ilomaspis narrator Grav., 

 //. narrator var. subalpina Schm: Tryphon consobrinus Hgn. T. brunnwentris 

 (jr. var. incestus Hgn. Lissonata dubia Hgn. Glypta resinana Htg. Phoeogenes 

 osculator Thnbg. Meteorits albilarsis Curt. IJadtodactylus flavifrontator Thbng 

 and from cocoons attached in great numbers to the branches of the spruce- 

 trees Pvgostolus sticticus F. was hatched. 



