30 
“Tmago. Cone Il, Fig. 3, f, g, h andi). Female. Length of 
body, 2.8 mm.; expanse of wings, 4 mm.; greatest width of front 
wing, 0.7 mm.; antenne, sub-clavate, three-fourths the length of 
thorax; whole ‘bod (with the exception of metanotum, which is 
finely punctate,) highly polished and sparsely covered with long 
hairs toward end of abdomen; abdomen longer than thorax, and 
stouter. Color, pitchy-black; scape of antenne, occasionally a small 
patch on the cheek, mesoscutum, femoro-tibial articulations, cox 
above and tarsi (except last joint) tawny; pronotal spot large, oval, 
and pale yellowish in color; wing veins dusky yellow and extending 
to beyond middle of wing; sub- marginal three times as long as mar- 
ginal; post-marginal very slightly shorter than marginal, and stigmal 
also shorter than marginal. 
Described from twenty-four specimens. Of these twenty-four 
specimens, only one was fully winged; two were furnished with hind 
wings only, and the rest were wingless. Male unknown. 
arva.’ (Plate Il, Fig, 3, a, b, c, d and e). Length, 4.5 mm. 
(nearly + inch); of the shape indicated in Fig. 3. Color, pale yel- 
low; mouth parts brownish. Antenne appearing as short, two- 
jointed tubercles. Mandibles with two teeth. Venter furnished with 
a double longitudinal row of stout bristles, a pair to each joint. 
Each joint bears also, laterally, a short bristle. Stigmata pale, 
circular; ten pairs, one on each of joints 2 (mesothoracic) to 11.” 
Pupa. (Plate I, Fig. 4). The mature pupa is 3 mm. in length 
by .8 mm. in transverse diameter.. It is of a wasp-like form, and 
differs but slightly from the wingless imago, except that the legs 
and antennz are applied closely along the under surface and sides 
of the thorax and abdomen, and are inclosed in a thin, transparent 
pellicle. The general color is jet black, and the various spots and 
markings of the imago are visible through the pupal envelope. This 
is in fact so thin that it does not conceal even the hairs upon the 
abdomen. 
LIFE HISTORY. 
As is clearly apparent from the foregoing, this insect is unques- 
tionably single-brooded, the eggs doubtless being laid upon the wheat 
in April and } May. The young larve penetrate the stem, develop 
and mature within the straw, commence to transform to pupe as 
early as October, and apparently complete their transformation 
before spring. In March and Aprii the perfect insect emerges, 
peculiar seasons and exceptional conditions haying, however, the 
ordinary effect to retard or hasten the transformation. 
Our own observations upon the life history of the species fully 
confirm the latest conclusions of Profs. Riley and French. Early 
in July the larve were found in the wheat stubble and straw near 
Du Quoin, Anna and Villa Ridge, in Perry, Jackson and Pulaski 
counties, in Southern Illinois, and numbers of specimens were sent 
alive to the Laboratory, where they were placed in breeding cages 
and kept without especial treatment, at the ordinary temperature of 
the air, during the summer, fall and early winter. When examined 
in January, all the larve still remaining unchanged were dead, and 
all the living Isosomas were in the pupa form, with the exception 
