1912] The Pezomachini of North America 129 
Pezomachus flavocinctus Ash. 
2 Proc. U.S. Nat. Mus. Vol. 12, p. 421. 
o& The male of this species is polymorphic, the specimens seen 
however fall into two main categories, namely (1) winged (2) wingless, 
while a single specimen was found in which the mesothoracic wings 
were present, but much smaller than normal, while the metathoracic 
pair were entirely absent. 
There is very little uniformity in details in this species but in general 
appearance and color members of both categories are very similar. 
The most constant characters are: 
1. The antennz, which are long and slender, and always about 29-jointed. 
2. The general shape of the head, which is about twice as broad as thick along 
the median line, is finely shagreened and has a sparse pubescence. The 
ocelli however, are inconstant in size. 
3. The ‘‘metathoracic’’ carina. This is not very prominent but is always some- 
what as shown in the figure, though it may be less angular. 
4. The legs are all rather long and slender, with very small simple ungues. 
5. The abdomen is densely pubescent in all forms and is mainly fuscous in color. 
The petiole and following two or three segments may have dull yellow 
apical bands. 
The most inconstant characters are: 
1. Ocelli. These are usually large in winged forms and quite small in wingless 
forms, but this correlation is not entirely constant. 
2. Mesothorax. The development of this varies immensely with the presence or 
absence of wings. The “‘scutellum”’ also is very large in winged forms, but 
tuberculate in wingless forms. 
3. The petiole. The spiracles may be, and usually are, tuberculate, but in some 
specimens they are hardly if at all prominent. This is inno way correlated 
with the presence or absence of wings. 
4. The size of the individual. Winged forms are typically the larger and vary in 
length from 4.5-5 mm. Some specimens however, are much more slender 
than others. The wingless forms vary from 3.5 to 5 mm. in length. They 
are all slender, but some are more so than others. 
Typical winged form. 
Length 4.5mm. Fully winged. Color mainly fuscous, but abdom- 
inal segments may have narrow yellow apical bands. Pubescence short 
and dense especially on the abdomen. ; 
Head from above finely shagreened, about twice as wide as thick 
along the median line. Occiput not very deeply excavated. Ocelli 
usually very large, placed on a somewhat raised triangle. The lateral 
ocelli nearer to the median than to the eye margins. Antenne long 
and slender, about 29-jointed; apex piceous, in some specimens this 
color extends almost to the base. Seventh and neighboring flagellar 
segments about 214 times as long as broad. Face rather lighter in 
color than the vertex. Malar line distinct about 4 to 3 as long as the 
face is wide as the lower end of the parallel inner eye margins. Clypeus 
transverse with a distinct basal fovea separating it from the remainder 
of the face. Mandibles bidentate, concolorous with, or a little more 
yellow than, the remainder of the head.’ Teeth somewhat darker. 
The face may have a longitudinal median swelling running from the 
insertion of the antennz to the base of the clypeus, at which point it 
is widest. 
