70 GALL-FLY. 



outline sketch of Insect Magicians by one or two of the most 

 plausible conjectures, as to the manner in which their natural 

 miracles are wrought through the prick of a needle, fit only 

 for the fingers of Queen Mab. 



The Ovipositor, or egg-inserting piercer, of the mother Grall> 

 fly, is, in some instance^Pbonspicuously long ; in others, only 

 partially visible, except on pressure, when it appears issuing 

 from a sheath, in form of a small curved needle longer than 

 the insect's body, wherein it is, however, rolled up by a curi- 

 ous internal apparatus. It is supposed, by Mr. Kennie,* that 

 " after the Gall-fly has made a puncture with this instrument, 

 and pushed her egg into the hole, she covers it over with some 

 adhesive gluten; or that the egg itself, as i^usual among 

 moths, &c., may be thus coated over. In either of these cases 

 the gluten will prevent the sap that flows through the punc- 

 ture from being scattered over the leaf, and wasted ; and the 

 sap, being thus confined to the space occupied by the eggs, 

 will dkpand and force outwards the pellicle of gluten that con- 

 fines it ; till, becoming thickened by evaporation and exposure 

 to air, it at length shuts up the puncture, stops the further 

 escape of the sap, and the process is completed." The above 

 explanation is, however, only given as conjectural, and the 

 one generally adopted by French naturalists is, that the gall 

 tubercle is caused by irritation, in the same way as an in- 

 flamed tumor in an animal body. 



* Insect Architecture, p. 371-3. 



