The Distribution of the Sexes 



vides her grubs with a heap of Plant-lice; 

 Try poxy Ion jigtdus, who feeds them with 

 Spiders. 



Soleniiis vagus digs her gallery in a bram- 

 ble-stick that is lopped short, but still fresh 

 and green. The house of this Fly-huntress, 

 therefore, suffers from damp, as the sap enters, 

 especially on the lower floors. This seems 

 to me rather insanitary. To avoid the hu- 

 midity, or for other reasons which escape me, 

 the Solenius does not dig very far into her 

 bramble-stump and consequently can only 

 stack a small number of cells in it. A series 

 of five cocoons gives me first four females 

 and then one male; another series, also of five, 

 contains first three females, with two males 

 following. These are the most complete that 

 I have for the moment. 



I reckoned on the Black Psen, or Psen atra- 

 tus, whose series are pretty long; it is a pity 

 that they are nearly always greatly interfered 

 with by a parasite called Ephialtes tncdiator.^ 

 I obtained only three series free from gaps: 

 one of eight cocoons, comprising only fe- 

 males; one of six, likewise consisting wholly 

 of females; lastly, one of eight, formed ex- 



»Cf. The Life of the Fly: chap, il— Translator's Note. 



lOI 



