202 MAINE) AGRICULTURAL EXPERIMENT STATION. 1916. 



ticular kind of food on which they may thrive. Certain kinds, 

 to take an example, glue their eggs to the surface of parts of 

 plants which are infested with plant-lice or aphids. In this 

 case they may be actually placed among the aphids or, more 

 often, on a part of the leaf or stem within easy crawling dis- 

 tance of the aphids. The eggs of other species are laid upon 

 moist tilth, in the nests of other insects, in decaying wood, etc., 

 depending on the feeding habits of the forthcoming young. 



In whatever situation found, the eggs of Syrphidae have a 

 somewhat characteristic appearance as indicated by Figs. 30- 



i, 2, 3; 3i-<^ 62, f>3'> $2-41, 4 2 > 4^; 3 6 - J > * 3; and 37- 

 /, 2, 3. They are chalk-white, shiny, elongate-ovate or sub- 

 cylindrical with rounded ends. The micropylar end more trun- 

 cate. Flattened slightly to the surface on which they are de- 

 posited, slightly humped above. Commonly about i mm. 

 (1-25 inch) long by a third of a millimeter in diameter, so 

 small that they are seldom noticed yet they can easily be seen by 

 the unaided eye. However, when viewed under a microscope 

 the characteristic thing appears; viz., a delicate and beautiful 

 sculpturing of the shell (chorion) consisting typically of ele- 

 vated oval areas (bodies) separated by depressed areas, but 

 each elevation surrounded by radiating and interlacing, some- 

 times branched arms, also elevated, which they give off into the 

 depressed areas and which often completely cover the latter 

 with a fine elevated network. 



(2). The Larva. Upon hatching there appears from the 

 egg, not a miniature fly as some might expect, but a very small, 

 slender, headless, footless, blind, creeping maggot, known tech- 

 nically as a larva. The exertions of splitting the shell and 

 escaping from the egg may require a brief rest; but very soon 

 the larva seeks out the food-supply. There follows a period of 

 almost constant feeding, covering from one to several weeks, 

 during which the maggot increases many hundreds of times in 

 size and deposits within its body a great excess of fatty mate- 

 rial of use in the third stage. 



The larvae of the different species are by no means all simi- 

 lar in appearance. In fact they differ so much that no one 

 would suspect some of them of being 1 the young of closely- 

 related flies. All of them agree in being cruciform, slug-like, 

 without true legs and only the most rudimentary of pro-legs or 



