2 BULLETIN 424, U. S. DEPARTMENT OF AGEICULTUEE. 



bears a strong, sharp spine on each side. In the female the antennae 

 reach the apex of the abdomen, while in the male the}^ reach a fourth 

 of an inch or more bej^ond, 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 4 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 is 

 yellowish or light brown in color. 



THE LARVA. 



The newl}^ hatched lar^'a 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) longby O.OT inch (2 milli- 



FlG. 1. 



-The Cottonwood borer {Plectrodera scalator) 



fOrisrinal. ) 



Larva, lateral view. Enlarged. 



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 pup8& 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- 



