INSECTS PREYING ON THE ORANGE APHIS. 



185 



FTQ. 85. The 

 Pruinos* 

 A p h i a - fl y, 

 larva. (Orig- 

 inal ) 



Larva. The maggot has the form and smooth surface of B. lugens, 

 but is more transparent and lighter in color, yellowish-green and white 

 predominating. 



THE PRUINOSE APHIS-FLY.* 



[Figs. 85 and 86.] 



A very common enemy of the Orange Aphis is a small two-winged 

 fly. Its young is a greenish, slug-like maggot, 3 mm (Jfo inch) in length ; 

 the body is flattened beneath, convex above, with two deep longitudinal 

 furrows on the back ; the joints of the head and neck are 

 small and tapering, as in the larva of Syrphus, and can be 

 greatly extended or entirely withdrawn into the body; the 

 body behind is rather broadly rounded ; from the upper 

 surface near the hind margin arises a pair of diverging 

 appendages like the horns of a snail ; the ends of these 

 appendages are open pores, and the apparatus constitutes 

 the principal spiracles, through which the animal breathes ; 

 the surface of the larva is roughened with minute knob- 

 like excrescences. 



When ready to transform into pupa, the larva glues it- 

 self to the surface of the leaf by means of a black gum. 

 The body of the larva shortens and thickens, becomes oval 

 in shape, and assumes a golden-brown color, the breathing tubes are 

 now very prominent, the lateral furrows of the larva are not obliter- 

 ated, but divide the puparium into longitudinal lobes, and appear as 

 broad bands of darker color upon the surface of the casket. 



When vacated by the fly the puparium splits in a ring near the an- 

 terior end, releasing the tip in the form of a conical cap the cap also 

 splits across the middle, dividing into 

 two valve-like halves, only one of which 

 is usually thrown off by the fry in its 

 exit. 



The fly (Fig. 86) is a small, thick 

 bodied insect, about 2 mra ( T Q inch) in 

 length, with deep purple eyes, transpa- 

 rent wings, and particolored legs; tho 

 body is bluish-white (pruinose), with 

 sparsely placed black hairs ; the upper 

 surface of the thorax is marked with 

 four longitudinal stripes of umber- 

 brown. The egg is white, elongate oval, with fine longitudinal lines ; it 

 is fastened to the surface of the leaf among the living Aphis. 



Transformations. What has been said of the habits and transforma- 



*Dr. S. W. Williston writes concerning this species: "They are evidently An- 

 thomyida, but I cannot place them in any of the European genera. I am acquainted 

 with a number of the Authomyid genera, but this species differs from any I know iu 

 the few bristles on the head and faqe." 



Fio. 86. The Prninose Aphia-fly. 

 inal.) 



(Orig- 



