4 PHYLUM ARTHROPODA 



Class : Tracheata. Division : Insecta. Order : Coleoptera 

 A LARGE BEETLE 



Compare the animal with the wasp. We notice in the first 

 place the heavier and clumsier body and the smaller head. The 

 animal is evidently much less active and also less intelligent than 

 the wasp. We notice also that the wings lie close to the body 

 instead of being raised above it. The forward, or meso thoracic, 

 wings are hard and thick ; they are not used for flight, but cover 

 the metathoracic pair and the hinder part of the body and thus 

 form an additional protection to the back. They are called the 

 wing-covers, or elytra. The entire body of most beetles, in fact, 

 has a thicker cuticula and, consequently, a more effective ex- 

 ternal covering than that of the wasp. This feature may be cor- 

 related with the smaller intelligence of the animal. Opening the 

 elytra, we notice beneath them the membranous metathoracic 

 wings with which the animal flies ; we notice also that they are 

 folded transversely as well as longitudinally. These wings are 

 wanting in some of the running beetles, where the wing-covers 

 are sometimes fused. Note the scutellum, the small triangular 

 plate between the base of the wing-covers. Find the eyes and 

 note their small size. Are ocelli present ? Find the antennae ; in 

 some beetles they are often concealed beneath the sides of the 

 head. 



Exercise 1. Draw an outline of the dorsal aspect of the beetle on a 

 scale of 4 or 5. First, however, spread and pin the right wing-cover 

 and wing. Number the thoracic and abdominal segments and label 

 all the parts observed. 



Exercise 2. Draw an outline on the same scale of the ventral aspect 



of the beetle, tracing carefully the sutures between the segments. 



Number the thoracic and abdominal segments. 

 Exercise 3, Remove a mesothoracic leg and draw an outline of it on 



the scale of 5. Label the segments. 

 Exercise 4. Remove a wing and draw an outline of it on a scale of 5, 



tracing in the veins. 



