FOR WAGGONER’S BIOLOGY 
67 
II. The External Structure. 
1. What are the size, the position, and the shape of the head? 
How is the head attached to the body? Is it movable? Note the 
slender feelers or antennce. What are the number and the location 
of the antennae? How many segments are there in each? Locate 
the compound eyes. These are upoti the sides of the dorsal region 
of the head. Locate the three simple eyes, the ocelli. Two of these 
lie between the compound eyes, just anterior to their dorsal part. 
The other lies in a depression in the median line of the face.” 
Examine the compound eyes with a lens and note the facets of 
which they are composed. Draw some of them. Study the mouth 
parts. Locate the labrum, or upper lip; the labium, or lower lip; 
the mandibles, or jaws, which are just below the labrum; and 
the maxillce, or little jaws, just below the mandibles. How do the 
mandibles open? Note the appendages of the mouth parts, the 
palpi. How many are there? What are their location and ar¬ 
rangement? Are the mouth parts adapted for sucking or for 
biting? Explain. Draw both front and side views of the head. 
2. Compare the size of the thorax with that of the head. Note 
its divisions. The anterior segment is the prothorax, the middle 
segment is the mesothorax, and the posterior one is the metathorax. 
What are the position and arrangement of the wings? Compare 
the pairs as to size, texture, and use. Remove them carefully and 
draw one of each. (Extend the back wing.) What are the posi¬ 
tion and arrangement of the legs? Compare the three pairs as to 
their size, use, and structure. In each leg the small rounded part 
nearest to the body is the coxa. Next to this is the trochanter, a 
still smaller segment. The third and longest segment is femur. 
Beyond this is the tibia. The remainder of the leg is the tarsus. 
What is the use of the “ claws ” and of the '' spines ” on the legs? 
Draw a hind leg. Draw the thorax from the side. 
3. What is the shape of the abdomen? What is its size as com¬ 
pared with the thorax? Of how many segments is it composed? 
In the female specimen, note the end of the abdomen. The four- 
pointed structure is the ovipositor. How is it adapted for deposit¬ 
ing the eggs? Find the spiracles, the breathing pores. What are 
