450 



A, viii, 225], and also suffered from other enemies, including a sawfly, 

 Acanlhoh'da crythroccphala, L., and the nun moth, Liparis {Lymanlria) 

 monacha. The resultant weakening of the trees also favoured beetle 

 infestation. 



The investigations here described took place on the author's own 

 property near Putten, where many species of Pinus, Picca and Abies, 

 and Pseudotsiiga doitglasi occurred, though as Piniis sylvcsiris formed 

 99 per cent, of thestands there was no mixed forest in the ordinary sense. 



Examination of the material beneath the moss cover showed that 

 the normal fauna feeding on green ])inc needles had been displaced by 

 P. flammca and A. erylhrocephala. A second striking fact was that 

 the total number of pupae of Panolis and their parasites was greater 

 after em infestation of one yeeir than after one of two years, possibly 

 owing to the decrease of suitable food. The moths also appear to 

 prefer unattacked trees for oviposition. 



The material found in February and March 1919 included the 

 following : living and dead pupae of Panolis and cocoons emptied 

 or abandoned by parasites ; full and empty cocoons of a Braconid, 

 Meteorus albiditarsus, Curt., and of an Ichneumon, Banchns femoral is, 

 Thoms., and cocoons of Panzer ia riidis, Fall. All the above parasites 

 are connected with Panolis. Furthermore, there were pupae and 

 numerous larvae of Acantlwlyda crytliroccphala, showing that the pupal 

 period of this sawfly was about to begin ; some of the larvae were at 

 some depth in the ground, and they seem to hibernate twice (and 

 perhaps three times) before pupating. The cocoons of an Ichneumon 

 parasite of A. erythrocephala, Xenoschesis fulvipes, Grav., were seen. 

 There were a few larvae and pupae of A . pinivora, Ensl., but they did no 

 injury in the present case. This species hibernates two or three times 

 before pupating. A few cocoons of another genus of sawfly, Lophyrus, 

 including two of Lophyrus neuiormn, L., were also noticed, and some 

 hibernating queens of Vcspa riifa, L., were occasionally found. 



In the spring of 1920 special attention was paid to Panolis and its 

 parasites mentioned above, it being also observed that the other insects 

 were exceedingly few. On an area of roughly 100-200 square yards 

 627 pupae of P. flammea, 817 cocoons of M. albiditarsus, 168 cocoons 

 of B. femoralis, and 1,745 pupae of Panzeria riidis were collected. 



The cocoons of P. flammca ^delded 240 living moths, 212 moths 

 shrivelled and dead, and 32 dead pupae. The following Ichneumonid 

 parasites were also obtained : 134 Ichneumon pachyments, Ratz., 

 four Exochilum circumflexum, L., one undetermined specimen (section 

 Ophionin.\e), and one Microcryptus arrogan's, Grav. 



The cocoons of M. albiditarsus yielded more than half their number 

 of the Braconid itself and the following Ichneumonid hyperparasites : 

 numerous specimens of Microcryptus arrogans, Grav., one each of 

 M. perspicillator , Grav., Hemitelcs sp., H. castaneus, Tasch., Angitia 

 tenuipes, Thorns., and Astiphromma strenuum, Holmgr., and two of 

 Hemitelcs pedestris, F. 



The cocoons of Banchus femoralis yielded the following Ichneumonid 

 hyperparasites : nine Microcryptus arrogans, one Hemiteles castaneus 

 and one of an undetermined species. 



The pupae of Panzeria rudis yielded adults in over 90 per cent, of the 

 cases. From thirty to forty of them an Ichneumonid was obtained 

 that Smits van Burgst determined as a new species of Phygadeuon ; this 

 may be a parasite special to P. rudis. Other hyperparasites included 

 two specimens of H. castaneus, and numerous minute Chalcids. 



