Fig. 4 (Right).—A common Illinois 
termite, Reticulitermes flavipes. A, 
winged queen; B, worker nymph; C, 
winged queen. B and C are natural 
size. (From Illinois Natural History 
Survey Circular 39) 
oD 
B a 
C y D 
Fig. 6—Diagnostic parts of worker ants. A, Labidus, front 
view of head; B, Labidus, enlarged view of bases of antennae; 
C, Camponotus, side view of petiole and gaster; D, Camponotus, 
nozzle-like anal opening at tip of abdomen. 
delineating several sclerites, always including a 
large V-shaped or U-shaped scutellum (Fig. 3) 
selec gg o lea heh asses See aE ects “pean ogee females 
Wingless, lacking wing stubs (Fig. 2) ; dorsum of 
thorax without a scutellum and associated scle- 
rites workers 
SYNOPTIC KEYS 
The following keys include all of the genera known 
from Illinois and a few others that are known to occur 
not far from this state and may ultimately be found here. 
Because most of the Illinois ants have a wide distribution, 
this synopsis should be helpful for the entire Midwest. 
The only North American subfamily not represented in 
these keys is the southwestern subfamily Cerapachyinae. 
Fig. 5 (Left).—Worker of Pseudo 
myrmex. A, side view; B, fron 
view of head (at right angles t 
greatest length). 
This subfamily contains only two genera in North Ameri 
ca, Cerapachys and Acanthostichus, whose workers an¢ 
queens may be distinguished by the spines on the latera 
margins of the terminal abdominal sternum. 
The genera treated in this synopsis have been num 
bered serially. To facilitate referring from the keys t 
the generic synopses, the genera have been given th 
same numbers in the keys as in the following synopse 
KEY TO SUBFAMILIES AND GENERA (WORKERS) 
1. Petiole two segmented (Fig. 2 and 5) 
Petiole one segmented (Fig. 7C, D, and E) 
2. Head with long, smooth eyes; antennae always clos 
together at base; scape little more than ha 
length of head (Fig. 5B) ; medium-sized to lars 
ants of wasplike appearance (Fig. 5A) (sul 
family Pseudomyrmecinae)........--+-:-- y 
Head shorter, eyes no larger than in Fig. 10; bas 
of antennae frequently well separated (Fig. 10 
antenna usually with scape longer, frequent 
longer than head ............. 3) 33a 
3. Compound eye represented by only one facet or a 
sent (Fig. 64); a pair of high, sharp ridg 
arising from head between antennal bases (Fi 
6B) (subfamily Ecitoninae) 
Compound eye represented by more than a sing 
facet (Fig. 10); head without high ridges li 
those in Fig. 6B (subfamily Myrmecinae) .. : 
4. Genital opening small and circular, surrounded - 
stiff hairs forming a terminal nozzle (Fig. 6C al 
D) (subfamily Formicinae) 
Genital opening slitlike or inconspicuous (Fig. 7) - 
5. Gaster with a distinct constriction between first 4 
second segments; abdomen with a well-develop 
sting (Fig. 7) (subfamily Ponerinae) 
Gaster without a constriction between first and s 
o 6 © 6) 0 oe 8 
oe © 6 0 «4 Ww) 
Peo 
. 7 eS 
