Pomona College Journal of ENTOMOLooy 613 



black, with dorsal arista. Thorax iridescent green, covered with fine long hair. 

 Legs — Coxae dark ; bases of femora dark ; remainder of legs amber brown. 

 .\bdoinen rich shiny black with three pairs of transverse yellow bands along the 

 dorsal margins. These bands do not unite in the middle by one-half their lengths. 

 There are also two very narrow transverse yellow bands extending across the 

 dorsum near the posterior or anal end. 



This, too, is a very common and widely distributed species and has been 

 reported from nearly every section of this country. 



Specimens were reared from twigs infested with Macrosiphiim citrifolii Ashm., 

 Toxoptera aurantiae Koch, and Aphis gossypii Glover as well as from a great 

 number of infestations of other common aphids. 



A 



Figure 204. A, Syrphus americanus; B, Allograpta obliqua 



Allograpta obliqua Say 

 (Figure 204. B) 



This is the smallest of the three species taken from citrus aphids. It is not 

 as plentiful as either of the two species above, but is by no means rare. Length 

 one-quarter of an inch. The body is dark and very slender. Eyes dark red. 

 Face yellow with dark median line. Antennae amber brown. Thorax iridescent 

 green. Scutellum light yellow. Legs light yellow. Abdomen dark with four 

 transverse yellow bands on the dorsum and yellow longitudinal markings at the 

 base of the ovipositor, which is amber brown or dark. 



Reared from Toxoptera aurantiae Koch and Aphis gossypii Glover. 



INTERNAL PARASITES 



Of the natural enemies of the citrus plant lice, by far the most effective are 

 the internal parasites. The adult females of these true parasites deposit their eggs, 

 by means of a long, sharp-pointed ovipositor, which pierces the body wall of the 

 lice, within the living tissues, inside the bodies of the plant lice. The outside 

 wound heals over in a short time leaving the egg tightly sealed within the body 

 ready to h«tch. As soon as the egg is hatched the small legless larva begins to 

 feed upon Ihe tissues of the aphid and its development means the extinction of a 

 louse. Wlien the larva is fully developed and ready to leave the "mummied" louse 

 it cuts a circular hole in the top of the body and escapes a winged insect ready to 



