388 MR, J. B. GATENBY ON THE BIONOMICS, EBIBRYOLOGY, 



from one or more eggs laid by the host, which give rise each by a process 

 o£ fission to the large number of larvse found in the host's haemocoel. In 

 this paper I am describing the anatomy of the larva of a Braconid parasite. 

 The polyembryonic species so far known are all Chalcids or Proctotrypids, 

 none is a Braconid. The Aphidse and Coccidse are parasitized by a large 

 number of species of Braconidse of which the genus Apliidius is well known. 



Other genera of Braconids which parasitize the caterpillars of many moths 

 and butterflies are Microgaster and Apanteles. By far the greatest number 

 of Hymenopterous parasites on the larvse of common moths and butterflies, 

 such as Portliesia similis and Pieris hrassicce, belong to the Microgasteridse, 

 though among the parasites of moth larvae and pupae are many Chalcids, 

 Ichne anions, and Tachinidse (Diptera). 



In this paper I have added some notes ou certain observations I have 

 made on an Apliidius of Aphis pomi, the reddish-brown aphis of the apple- 

 leaf. ' 



In several entomophagous internal parasites the larvae are peculiarly 

 modified for their modus vivendi, but I believe thiit the Microgasteridse are 

 among the most highly specialized, and the form with a large respiratory 

 bulb has never before been properly examined. The peculiar larva? of some 

 Proctotrypidas discovered by Granin (16) have within recent times been 

 re-examined by P. Marchal (19)/but, though they are very bizarre in shape, 

 I think that the tail vesicle of the Microgasteridee is the most remarkable. 



My thanks are due to Prof. Poulton and his assistants for some help and 

 for the loan of specimens of Aphid parasites. 



Bionomical Note and Previous Work. 



The Hymenoptera have among their number forms whose remarkable 

 habits and instincts have filled us with admiration. Though the instincts of 

 tne Hymenoptera Parasitica have rarely turned to a colonial life, they have 

 been directed almost wholly to the hunting and capture of prey, and to the 

 solution of many difficulties in oviposition, which might have been thought 

 insurmountable. The reason why very little is known about the bionomics 

 of Braconids, Chalcids, and Proctotrypids, is that they are almost all very 

 minute creatures^ and therefore very difficult to study successfully. More- 

 over, the Braconids especially are fairly shy insects, and it is often difficult 

 successfully to handle them in captivity. The method in which these 

 entomophagous parasites hunt their prey, the clever manner in which they 

 contrive to deposit their eggs inside the body of their victim, and the 

 curious individuality of method of procedure in different species, are alike 

 very remarkable. 



Porthesia similis is commonly called the ^' gold-taiP^ moth ; the eggs are 

 laid late in the year and the larvae hibernate. In spring they come to life 



