THE TOBACCO BEETLE. 19 



effort is made by the larvae 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 larvae. 

 On several occasions larvae were observed to leave partly formed 

 cells, crawl 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 larvae 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 (PL II, 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 pupae 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. 



