— 30' — 



tions do not allow any statement where the différent générations 

 parasitize in Denmark, but it is a fact that eggs of some Dytis- 

 cid, bug or Odonate, are always présent for each génération 

 of parasites. We might imagine the 3 forms to represent 

 seasonal variations but this does not seem likely as f.i. ail 

 3 forms may be found at the same time (end of July) and at ail 

 events the two varieties together through the month of August. 



As to the swimming habit of the imago I must state that it 

 dces not seem to me to swim cleverly or well. The females 

 vse their hind legs, but thèse long and slender legs having no 

 spécial adaptations for swimming move just like those of a house 

 fly rubbing and twisting its legs for cleaning purposes. 



Var. solitaria which by RUSCHA and THIENEMANN is sa ; c! to 

 swim ,, sehr geschickt und schnell " is, acccrding to my obser- 

 vations, the poorest in swimming. 1 often saw it walk along 

 stalks or sides of aquarium with long and eager steps, and it 

 swims by a violent exaggeration of the movements, but it is very 

 unwilling to swim and is upon the whole behind the other two 

 forms in this respect; it wriggles its body and advances much 

 more slowly than the others. The maies move distinctly sîower 

 than the corresponding females ; according to ENOCK they use 

 their middle legs in swimming. 



3. Agrioiypus armatus WaLK. 



This well known Ichneumon-fly is in Denmark found in Sker- 

 naa a': Rorbae so, at Aarhus (both localities in Jutland) and in 

 Lellinge Aa and in a broo near Fonstrup (both in Sealand). The 

 hosts were the Caddis-flies Silo pallipes and Goera pilosa. 



On 5i7o-cases, collected 12/5 — 15/5, I found when protracting 

 the Silo larvae that 10 of thèse were furnished with eegs of 

 Agriotypus armatus. The egg (fig. 5 A) is 0,7 mm in length, 

 rather elliptical and with a thin peduncle half of which is plun- 

 ged in the host and thus fixed to him. Around the plunged part 

 is seen a blackish brown sheath of coagulated lymph. Com- 

 monly only one egg was found on each larva, but in four 

 instances two eggs were found on the same larva. The spot 

 where the egg was fixed was rather varying, viz : 



1. Dcrsally right, on the hindmost part of metathorax, 

 Ventrally left, between 2. and 3. abdominal segment. 



