POSITION OP EGGS. 



45 



with a white transparent stem, more than an inch 

 high, not thicker than a human hair, but much more 

 stiff and rigid. About a dozen of these eggs are 

 deposited in a single and sometimes in a double hne, 

 upon the leaves and branches of elder or other trees 

 and plants abounding with aphides, upon which the 

 grubs feed when hatched. The footstalks of these 

 eggs are formed by the mother-fly attaching a drop 

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

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

 is deposited on its summit. As she uses her body for 

 a measure, 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 ( CoccineJlce) and of aphidivorous 

 flies {Syrphi), which frequent the same situations and 



Twig of lilac, bearing the eggs of the lace winged fly (Cfvypsnpa 

 rciicidata, Leach). 'i"he fly is seen resting on the lowest leaf. 



