Till: GENUS DENDROCTONUS. 57 



The metathoracic spiracle is not represented. Spiracles 3 to 8 are 

 exposed when the elytral pad is in normal position, but spiracles 7 

 and 8 are very small and obscure. Thus the pupa has the same 

 number of spiracles as the larva, while in the adult there is an addi- 

 tional one, although that of the eighth abdominal tergite is apparently 

 ^rudimentary. The larva has one thoracic spiracle, apparently in the 

 prothoracic segment. The pupa has one in the mesothoracic, and the 

 adult has one in the mesothorax and one in the metathorax. 



Legs. The front and middle legs are exposed, while the hind legs 

 are partially concealed beneath the elytra and wing pads. The front 

 coxae are large and contiguous, the anterior fourth covered by the 

 maxillae and labium, and the posterior margin extends over the 

 anterior margin of the mesosternum. The middle coxae are partially 

 hidden by the apex of the front tibia and its tarsus. The hind 

 coxa 1 are for the most part exposed, and distinctly separated by an 

 iniercoxal area. The positions of the different parts of the legs in 

 their relation to the exposed structures are shown in figure 37, and 

 are of considerable taxonomic importance. The apical and subapical 

 spines of the femora are also of considerable importance as distinc- 



; tive characters. 



LARVA. 



The structure and general characters of the larva are shown in 

 figure 39. It is of the subcylindrical, wrinkled, legless type common 

 to all of the true Rhynchophora, and also has the form of mouth parts 

 characteristic of the larvae of this suborder. There are three thoracic 

 and ten abdominal segments, the tenth being represented by the 

 anal lobes. The four longitudinal divisions, viz, one sternal, two 

 pleural, and one tergal, are clearly represented in all of the segments. 

 The tergal division occupies nearly one-half of the circumference, 

 the two pleural divisions together about one-fourth, and the sternal 

 division slightly more than one-fourth. The head is much narrower 

 than the first thoracic segment and but slightly longer. The three 

 thoracic segments together, or the thorax, is about one- third as long 

 as the abdomen. With the exceptions of the scattering hairs on the 

 head and on the scutellar lobes of the thoracic and abdominal seg- 

 ments, the body is without distinguishing vestiture. 



EXTERNAL CHARACTERS. 



Head (figs. 40, 41). The head is by far the most important part of 

 the body as a bearer of taxonomic characters in the larva. The gen- 

 eral structure is shown in figure 40, and the anatomical details in 

 figures 41 and 42. All of the primary elements of the adult head are 

 represented, but they are much more simple in their structural details. 

 The more striking differences in the larval head are found in the 



