May 5,1923 
Silver-Striped Webworm 
423 
TablB III .—Length in days of various stages and instars of Crambus praefectellus —Con. 
C. MISCELLANEOUS RECORDS. EGGS HATCHING APRIL 21 TO AUGUST 8 
Eggs. 
Larva. 
Larva- 
pupa. 
Pupa. 
Entire 
develop¬ 
mental 
period. 
Maximum.. 
IS 
38 
85 
18 
71 
Minimum. 
5 
27 
33 
9 
41 
Average. 
7 * 73 
31 - 5 
51 
II. 3 
51 - 5 
Number of records averaged. 
22 lots. 
14 
65 
21 
In addition to those included in the tables, the writer has records of a 
few individuals hatching on September i8, which emerged as adults be¬ 
tween January 23 and February 26 of the following year, after having 
been kept in the cool room of the insectary all winter. 
It will be noted that most of these larvae pass through six instars be¬ 
fore pupation, but occasionally there is a seventh instar. The last instar 
before pupation is always much longer than those preceding, so that in 
order to make the averages correct these records are separated as normal 
and prepupal. 
Through an oversight, detailed color descriptions of the various larval 
instars except the first were not made. The molted head casts were 
preserved, however, and the following list of characters is drawn up from 
them: 
Table IV. —Head width of larvce of Crambus praefectellus 
Instar. 
Minimum. 
Maximum. 
Average. 
Number of 
heads 
measured. 
I.. 
Mm. 
0. 229 
•335 
• 529 
.882 
I. 306 
1-493 
Mm. 
0. 229 
.300 
•459 
•759 
•933 
I. 306 
Mm. 
0. 229 
•325 
.512 
.826 
I. 219 
I- 399 
Mm. 
(a) 
8 
7 
10 
15 
2 
II. 
Ill.:. 
IV. 
V. 
VI. 
o Large number measured, but exact number not known. 
In the first instar the head is shining black, paling somewhat but still fuscous in II. 
In III the ground color is still paler, with faintly darker areas indicating the later color 
pattern. In IV these markings have become much darker and more distinct, and the 
ground color of the head has become pale yellow. In the next two instars the colors 
remain the same, but become more intense. The color of the body of the larva through 
most of its growing period is a dull brown with a greenish tinge from the contents. The 
arrangement of the pinacula and setae is shown in Plate i, A. 
THH PUPA 
The cocoon is a little case about the size and shape of a peanut meat, lined and 
stiffened with gray silk inside and outwardly covered with particles of eaiili. It gen¬ 
erally lies so near the surface that no ‘*neck’* or emergence tube is necessary. 
The pupa itself is very similar to others of this genus. Bright yellow when first 
formed, it soon darkens to a mahogany brown. A day or two before emergence the 
silvery stripe in the forewing becomes plainly visible through the covering. The 
