POSITION OF EGGS. 



45 



with a white transparent stem, more than an incli 

 hiiih, not thicker tlian a human hair, l)nt nuicli more 

 stili" and rif^iil. About a do/en of ihof c^^gs are 

 de|)ositcd in a single and sometimes in a double Hne, 

 upon the leaves and branches ot" elder or other trees 

 and plants abounding with aphides, upon which the 

 grubs feed when hatched. The footstalks of these 

 eggs are formed by tlie mother-fly attaching a drop 

 of gluten to the hrancii, and drawing it out (as a spi- 

 der does its line) to the requisite length before the egg 

 is deposited on its sumjnit. As she uses her body lor 

 a measme, the footstalks are by consequence all near- 

 ly of equal length.. It is evidently the design of these 

 footstalks to place the eggs out of the reach of the 

 grubs of lady-birds {Coccinnlkv) and of aphidivorous 

 riies {Syrphi), which fiequent the same situations and 



•■Udavs) 



Twig of lilac, btariiig the eggs of the lace winged fly (CAtypsopa 

 riticutata, Leach). Ihe tly is sctn resting on the lowest leaf. 



