14 BULLETIN 737, U. S. DEPARTMENT OF AGRICULTURE. 
SPECIFIC CHARACTERS. 
Median region of epistoma with a row of five setz on each side, lateral 
regions naked; labrum with about seven straight setze on the upper surface at 
each anterior corner, several long, medianly curved sete along the anterior 
margin and an oblique row of three, shorter, stouter, hook-shaped sete on the 
under surface on either side of and posteriorly approaching the median line; 
eclypeus naked; stipes labialis, mentum, and submentum with long soft sete; 
maxillary articulating area not setiferous. 
LARVAL INSTARS. 
First-instar larva 0.55 to 1.4 mm. long; yellowish white; the digestive tract 
showing darker; body set sparsely with very long, pale hairs; head 0.12 to 0.16 
mm. long. Second-instar larva about 3 mm. long; yellowish white; head 0.22 
to 0.24 mm. long. Last-instar larva about 4 mm. long; yellowish white; set 
entirely with long, silky, yellowish brown hairs; chitinous parts brown; 
spiracles concolorous with body; head 0.5 to 0.7 mm. long. 
THE PUPA. 
Pupa (Pl. Il, fig. 2) uniformly white when first transformed. Length (aver- 
age) 3.5 mm. (2.5-3.75 mm.); width about 1.7 mm. (1.1-2 mm.); tips of 
elytra attaining fourth visible ventral segment of abdomen. Metathoracic legs 
beneath the elytra not attaining tips of inner wings. Head bent upon thorax 
and beneath pronotum. Ultimate and penultimate abdominal segments ven- 
trally each with a pair of fleshy lateral protuberances. 
THE ADULT.1 
CE ess stexctctilee cde) 
Elongate-oval, moderately convex. Uniform dull reddish yellow or brown- | 
ish red. Head broad, eyes small. An- 
tenn rather narrow, second and third 
joints smaller than first, the third dis- 
tinctly triangular; fourth to tenth 
about as wide as long; eleventh oval. 
Thorax strongly convex, front angles 
EE rele TEC Bueet cua cote acute, hind angles wanting. Punctua- 
ee : Me ieanek of anu scaly efor (Ot entire upper surface fine, uni- 
enlarged. ~ form, not dense. Length 2.2 to 3 mm. 
LIFE HISTORY AND HABITS. 
SUMMARY OF LIFE HISTORY. 
The life history of the tobacco beetle may be briefly summarized as 
follows: , 
In material kept constantly warm, breeding is continuous and 
there may be as many as five or six generations in a year. Under 
usual conditions in warehouses in the latitude of Virginia there are 
ordinarily three or four generations a year. The beetle lives in its 
food substances during all stages of its existence, and the time re- 
quired to complete its life cycle depends mainly upon temperature 
and may be as short as 45 days. Normally, in summer, the time 
1 Description of adult by W. S. Blatchley (71). 
