226 MR. A. M. ALTSON ON THE LIFK- HISTORY AND 



the liind-legs is sometimes chniiged, and they are placed further 

 apart so as to lower the boily in rhythm. During this movement 

 the abdomen gradually assumes an extraordinary lateral aspect 

 until, when the ovipositor is completely inserted, its appearance is 

 similar to that depicted in text-fig. 19. The flexibility of the 

 sternites is remarkable. Sometimes, after the ovipositor has 



Text-figure 19. 



Female N. hrevicornis ovipositing; 2iul position. Greatly magnified. 

 Original. 



been inserted its full length, it is partly withdrawn, and appears 

 to be moving slowly in a circle, giving the impression that at this 

 time the eggs are being discharged so as to lie together in a 

 cluster but not on top of each other. Eventually, by lifting the 

 abdomen till it recovers its position as shown in text-fig. 18, 

 and then lifting the thorax with the hind-legs, it disengages the 

 ovipositor, which instantly springs back to its normal hidden 

 position. 



Generally a minute drop of clear liquid appears at the point 

 of insertion of the ovipositor directly it is withdrawn, but the 

 female moves backwards over the hole until it is located by her 

 palpi or antennae, and then appears to " suck up " the liquid 

 The drop of liquid is not always visible, and the nature of it has 

 not been determined. 



One observer says : — " This liquid is probably used in the first 

 case as a lubricant by bathing the styles as they work on the 

 sheath while puncturing " (8). Another : — " The liquid is either 

 a fluid resembling in its nature a synovial fluid, or else it had 

 been acting as a lubricant for the styles ; the former is the more 

 probable " (7). Another observer says : — " In many cases it (the 

 hole) became covered with a white mycelium-like growth the 

 nature of which we have not determined " (6). That the func- 

 tion of the liquid is to seal the hole seems probable. Only in 

 three instances amongst material parasitized in the open liave 

 mites (undetermined) been found inside intact puparia inhabited 

 by developing Chalcids, and in one case a pupa had been partially 

 devoured. 



The time occupied in ovipositing is variable, ranging from a few 

 seconds to half-an-hour. A few specific instances are quoted : — 

 " The deposition of an egg observed at 9.45 p.m., Sept. 14, 

 required 16 minutes; the host was Phormia regina. Another 



