A SYNOPSIS OF THE APHIDIDAE 115 



132. Aphis middletonii Thomas 



Figures 219, 220 

 Thomas, 8th Ann. Kep. 111. St. Ent., p. 99, 1879 (orig. desc.). 



Recards. Amaranthus retro flexus ; Santa Paula, August, 1911 (Essig) : Ban- 

 unculus calif ornicus; Julian, San Diego County, June, 1916: Hemizonia rudis; 

 Stanford University, 1916 (Ferris) : Helianthus annuus; Kiverside, September, 

 1916. 



In the fall of the year this species is rather common on the roots 

 of various plants in California. The individuals are small green 

 aphids, covered with a slight pulverulence. They are very similar 

 to Aphis maidis-radicis Forbes, with which they have often been con- 

 fused, and differ particularly in the presence of secondary sensoria 

 on the fourth antennal segment of the apterae. Below are a few 

 descriptive notes taken from specimens mounted in balsam, collected 

 in 1916 in Julian and Riverside, and in 1911 near Santa Paula: 



Alate viviparous female. Greenish, pruinose. Head, antennae, 

 thorax, marginal spots on abdomen, cornicles, cauda, apical one-half 

 femora, apices tibiae, tarsi, and apex of beak, black. Antennae reach 

 to the base of the second abdominal segment; III being the longest 

 segment, followed by VI spur. IV and V are subequal, VI base 

 slightly shorter. The usual primary and accessory sensoria are pres- 

 ent. Secondary sensoria occur on III and IV (fig. 220). There are 

 nine to twelve on III, and one to four on IV. The average numbers 

 are eight and two respectively. The beak reaches to the third coxae. 

 Prominent lateral tubercles are present on the first and seventh 

 abdominal segments, as well as on the prothorax. The cornicles are 

 short and taper slightly toward the apex. They are subequal in 

 length to the hind tarsi, and very slightly larger than the cauda. The 

 wings are normal, with the second branch of the third discoidal arising 

 nearer to the apex of the wing than to the base of the first branch. 



Measurements: Body length, 1.65 to 1.7 mm. (av. 1.674 mm.); 

 width of thorax, 0.561 mm. ; antennae total, 0.816 to 0.918 mm. (av. 

 0.884 mm.) ; III, 0.204 to 0.255 mm. (av. 0.2338 mm.) ; IV, 0.11 to 

 0.119 mm. (av. 0.1169 mm.) ; V, 0.11 to 0.136 mm. (av. 0.1275 mm.) ; 

 VI, base 0.085 to 0.102 mm. (av. 0.0986 mm.) ; VI, spur 0.204 mm.; 

 cauda, 0.102 mm.; cornicles, 0.1275 to 0.136 mm. (av. 0.1332 mm.) ; 

 hind tarsus, 0.119 to 0.136 mm. (av. 0.1303 mm.) ; wing length, 1.904 

 to 2.38 mm. (av. 2.159 mm.) ; width, 0.731 to 0.85 mm. (av. 0.815 

 mm.) ; expansion, 4.3 to 5.1 mm. (av. 4.717 mm.). 



