72 Observations on Cynipidae. 



creeping up the trunks. They then seek by preference 

 the greater terminal buds^ and begin to bore into them. 

 The pricking is done in a very different way from that 

 of other gall-flies. After a suitable bud has been found, 

 the fly stops, turns with its head downwards, and 

 directs its abdomen to the point of the bud. In this 

 position it inserts its ovipositor somewhat below the 

 middle of the bud, and bores straight towards the base. 

 The egg comes to lie deep in the bud, in or upon the 

 tissue from which the terminal growth proceeds. After 

 the fly has pushed in its ovipositor it withdraws it, and 

 goes on boring one canal after another in the stratum 

 which the ^'g^^ is to occupy, until the whole layer is 

 riddled like a sieve. When the operation is finished, 

 the eggs are successively pushed into the pricked 

 canals, where they lie so thickly together that they 

 look like a continuous mass. The amount of work 

 which the fly goes through in laying its eggs in this 

 way is astonishing. After having been occupied for 

 hours in boring these numerous canals, it appeared 

 to me at first inexplicable that it had as yet laid no 

 eggs ; I found, however, that it bores all the canals 

 for their reception before actually laying a single ^%%. 

 This part of the work requires much time, as to which 

 I have made the following observations. 



On January 27, 1878, a fly was put upon a little oak, 

 and soon began to prick a bud ; when it had finished 

 the first bud, it went on without interruption to another, 

 and was altogether eighty-seven hours busily employed 

 in laying its eggs. In these two buds I counted 

 582 eggs. 



