A SYNOPSIS OF THE APHIDIDAE 



129 



Alate viviparous females. Measurments : Body length, 1.78 to 1.9 

 mm. (av. 1.86 mm.) ; width, (thorax), 0.95 mm.; antennae total, 1.38 

 to 1.51 mm. (av. 1.449 mm.) ; III, 0.34 to 0.425 mm. (av. 0.391 mm.) ; 

 IV, 0.238 to 0.273 mm. (av. 0.256 mm.) ; V, 0.212 to 0.229 mm. (av. 

 0.219 mm.) ; VI, 0.136 to 0.17 mm. (av. 0.155 mm.) ; spur, 0.255 to 

 0.306 mm. (av. 0.289 mm.) ; cornicles, 0.255 to 0.2975 mm. (av. 0.275 

 mm.) ; cauda, 0.2125 to 0.238 mm. (av. 0.225 mm.) ; hind tarsi, 0.153 

 mm.; wing length, 3.06 to 3.4 mm. (av. 3.19 mm.) ; wing width, 1.27 

 to 1.46 mm. (av. 1.338 mm.) ; wing expansion, 7.48 mm. 



30. Genus Toxoptera Koch. 

 Koch, Die Pflanzenlause, p. 253, 1857. Type Aphis aurantii Fonsc. 



152. Toxoptera aurantii (Fonsc.) 



Figures 114, 163, 276 



Boyer de Fonscolombe, Ann. Ent. Soc. France, vol. 10, 1841. Aphis (orig. 



desc.). 



Essig, Pom. Jour. Ent., vol. 3, p. 601, 1911. T. aurantiae Koch (desc.). 

 Davis, U. S. Dept. Agr., Bur. Ent., Tech. Ser., Bull. 25, pt. 1, p. 8, 1912. 



Records. Citrus spp. ; throughout citrus sections of southern and central Cali- 

 fornia (Essig, author) ; San Jose (Davidson). 



This is the common black louse of the citrus trees, and is found at 

 almost any time of the year on the younger and more tender leaves 

 of various species of Citrus. It is more or less heavily preyed upon 

 by the braconid fly, Lysiphlcbus testaceipcs Cresson. In fact, the 

 author has noticed several infestations in which fully ninety-five per 

 cent of the individuals were parasitized. Besides these the syrphid 

 flies cause great havoc among colonies. Of these the author has reared 

 Allograpta obliqua Say from a colony taken in the vicinity of El 

 Cajon, San Diego County. Never does this species become abundant 

 enough to seriously damage trees, due undoubtedly to the effective 

 work of its predacious and parasitic enemies. Only in the spring 

 are they found to any great extent, although occasionally throughout 

 the year small infestation can be noticed. 



