CLOVER STEM-BORER AS AN ALFALFA PEST, 11 
quick wriggling motion. The wall of the tunnel often becomes so 
thin as to cause wilting of the plant, and in such cases the stem 
usually falls to the ground, so that in an alfalfa field damaged by this 
insect the infested stems nearly always either fall on the ground or 
lodge one against another. 
The larva, upon the completion of its feeding period, constructs a 
cell within which to pupate. This cell is usually 8 to 10 inches long 
and is sealed at both ends with frass and excrement mixed with a 
secretion similar to saliva, which the larva ejects at the time of con- 
structing: the cell. 
It is impossible for either the larva or pupa of this species to con- 
tinue its development after a hay crop is cut and put in the stack 
or baled. During the fall of 1915 the junior author made many 
observations bearing upon this point, his record of which follows: 
During the past month many stems from hay stacks of the past season’s cutting 
have been dissected. In a large percentage of the stems there has been evidence of 
Languria injury, and in many of the stems larve and pup were found. These larve 
and pupze were all dead and dried up, giving evidence that the development is stopped 
when the hay is cut and put in the stack. Stalks from hay that has been baled have 
also been dissected and the above conditions are true of the baled hay also. 
PUPA. 
DURATION OF THE PUPAL STAGE. 
The pupal stage for all temperatures for a total of 130 specimens 
averaged about 9 days, as is shown in Table I, and also in Table V, 
which follows. Twenty-six specimens, during the months of July 
and August, averaged 5.6 days (see Table VI). The minimum 
length was found to be 3 days during the month of July with a 
maximum of 18 days during the month of June. | 
Pupation takes place within the cell constructed by the larva, 
requiring often several hours for the shedding of the larval skin. 
The larva first attaches itself by the anal cerci to the bottom of the 
tunnel, and by means of this attachment the pupa very easily de- 
taches itself from the cast skin. This last larval skin is always found 
attached at the place mentioned. 5 | 
The pupa is exceedingly active, and as in the case of the larva 
moves with freedom up and down this 8 or 10 inch tunnel by means 
of the wriggling movement which has already been mentioned as 
being characteristic of the larva. 
