THE TOBACCO BEETLE. 19 
effort is made by the larve to reach the surface of the food substance 
although many of the cells are constructed on the outside. In leaf 
tobacco the cells usually are formed along the midrib or in the folds 
of the leaf. In boxes of cigars, cigarettes, and smoking tobacco cells 
may be found on the sides of the boxes, often within the paper lin- 
ing; others may be found between closely packed cigars or cigarettes. 
The larva frequently cuts through the wrapper or binder of a cigar 
- from the outside, forming a cell just within the wrapper, the cell 
filling the opening made in the cigar. The pupal cells usually are 
ovoid, but vary considerably in shape and completeness, this depend- 
ing largely on the location of the larva and the character of the food 
substance. They average (inside measurement) about 4.5 millimeters 
long and 3 millimeters wide. They are often without definite shape, 
flimsy, and fragile, being constructed of small particles of the food 
substance and refuse cemented together by a secretion of the larve. 
On several occasions larvee were observed to leave partly formed 
cells, craw] a short distance, and form other cells in which trans- 
formation to the pupa stage finally took place. In leaf tobacco the 
cells frequently are incomplete, the larve utilizing folds of the leaf 
for part of the cell, and on flat surfaces they simply form coverings 
over themselves. Within dense substances the surrounding material 
forms the necessary protection, the walls of the cell being thinly 
lined. 
THE PREPUPA. 
Before transformation there is ordinarily a period of from 4 to 12 
days during which the larva within the cell undergoes structural 
changes preparatory to pupation. If exposed to low temperatures, 
as has been stated, the larva may remain in the cell for a consider- 
able time before marked change in structure or appearance takes 
place. Before changing to the pupa stage the larva lies in a curved 
position within the cell, which is large enough to permit free move- 
ment. The body contracts and becomes somewhat more deeply 
wrinkled. 
THE PUPA. 
When newly formed the pupa is white (PI. IT, fig. 2), but grad- 
ually it assumes a brownish tinge before transformation to the adult 
stage, the eyes becoming reddish or reddish brown. It lies on its 
back within the pupal cell. Should the cell be broken open and the 
_ pupa removed, transformation takes place in an apparently normal 
manner if protected from rapid evaporation. In handling infested 
leaf tobacco many bare pupz can be seen which have been dislodged 
from the fragile cells or cocoons between the leaves of the tobacco. 
After transformation has taken place a portion of the pupal skin 
frequently adheres for a short time to the tip of the abdomen, 
