l86 THE APPLE LEAF HOPPER 



In Drepanosiphum and Aphis frondosa there is a tnbercle on the pos- 

 terior side of the distal end of the femur. The hairs on the femur, 

 except in Lachnus and Melanoxanthus, are arranged in irregular 

 longitudinal rows. The long slender tibia is very hairy in some genera. 

 In MonelUa it has several spines at its distal end. A two- jointed 

 tarsus with an oblique suture between the joints is typical of .ipJiids. 

 The proximal joint which is about half as long as the distal one, is 

 generally set into the end of the tibia. In Chcrmes it is provided 

 with a pair of sucking disks. The distal joint has two long curved 

 claws, but lacks a pulvillus. In Pliyllo.vcro. Chcruics and Honnaphis 

 there is a pair of tenent hairs on the dorsal side of this joint not 

 far from its distal end. In Mastopoda the tarsus is represented by a 

 single short thumb-like joint. 



Minute circular (sensoria) similar to the ones found on the sec- 

 ond joint of the antenna, and on the wings, are found on the legs. 

 There are usually four on the trochanter, two dorsal and two ventral. 

 There may be from one to sixteen near the proximal end of the femur. 

 There are many different arrangements of these, so that it might be 

 possible to use them as specific characters in some genera. 



In the oviparous female of Ncctarosipluiiu rubicola. RJwpalos- 

 ipliiiiit hippopluv, CaUipterns trifolii, Toxoptcra gramiiiuui, Macros- 

 ipliu'iii pisi, and others the tibia of the hind leg is swollen for its 

 whole length, and is thickly dotted with clear pits which closely 

 resemble the sensoria of the antenncie. The tibia in this case has some 

 function in connection with oviposition. I have not been able to 

 examine the sexual forms of enough species to determine how far this 

 condition is characteristic of the oviparous female. 



The Abdomen: There are nine al)(li>miiial segments in 

 A l^hididcc. It is difficult to make out the exact nnnil)cr of segments on 

 account of the usual swollen condition of the abdomen. The first seven 

 segments are provided with spiracles, the first two of which are close 

 together. The fifth segment liears the cornicles. The eighth bears the 

 genital plate, while the ninth bears the anal plate and the cauda. 



Any one of the first eight segments may bear tubercles or glands. 

 Some genera, such as Drepanosiphum and CaUiptcnis have a pair of 

 prominent conical tubercles on the dorsal side of each of the first two 

 or three alxlominal segments. Each of these is tipped with a single 

 short stiff hair. On the dorsal part of the eighth segment in Siphoc- 

 oryuc arrhaiif/rlliccc there is a single tubercle tipped with two hairs. 



