2 BULLETIN 424, U. S. DEPARTMENT OF AGRICULTURE. 
bears a strong, sharp spine on each side. In the female the antenna 1 
reach the apex of the abdomen, while in the male they reach a fourth 
of an inch or more beyond, and the segments are thicker and longer. 
The male beetle is illustrated by Plate I. 
THE EGG. 
The egg is 0.12 to 0.15 inch (from 3 to 1 millimeters) long by about 
0.10 inch (2.5 millimeters) thick and is elliptical in shape. The outer 
covering is pliable, but very tough, being almost leathery. It 
3^ellowish or light brown in color. 
i> 
THE LARVA. 
The newly hatched larva is of the usual cerambycid form. In 
color it is white with black mouth parts and is much wrinkled trans- 
versely. It is about 0.20 in. (5 millimeters) long by 0.07 inch (2milli- 
FlG. 1. 
-The Cottonwood borer {Plectrodera scalator) : Larva, lateral view. Enlarged. 
(Original. > 
meters) across the widest part, which is just behind the head. Little 
change occurs in color during the larval stages, but the length 
may increase eleven times and the width five or six times, making 
the mature larva nearly twice as long in proportion to its width as 
the newly hatched larva. (Fig. 1.) 
THE PUPA. 
Of five pupae, the average length was 1.40 inches (3.5 centimeters) 
and the average width 0.80 inch (2 centimeters). When first formed 
the pupa is dull white, but the points soon become dark. The femur 
and tibia of each leg are folded against each other and placed trans- 
versely on the ventral surface of the body, with the tarsi extending 
backward beside the median line. The wingpads are folded ob- 
