A STUDY OF INSECT MOUTHPARTS n 



Taking the cabbage butterfly (Pieris rapa) as an example, the 

 labrum is seen to be greatly reduced, the mandibles absent. The 

 mandibles may be weakly present in the lower Lepidoptera. 

 The maxillae are apparently only represented by the galea, 

 which by the close approximation of their inner grooved surfaces 

 form the proboscis, long and coiled. The double structure of the 

 proboscis can easily be demonstrated by manipulation. The 

 labium is represented by the labial palpi. 

 Draw and label parts. 



E. Dipteron type. 



a. First subtype, the mosquito. The more generalized type 

 of Dipteron mouthparts is found in the mosquito, hence here we 

 find the maximum number of stylets or bristles, representing the 

 parts of the more generalized types, loosely ensheathed in the 

 elongated labium, the whole forming the prominent beak, or 

 proboscis. The identity of the six stylets is not well established, 

 though it is generally accepted that they represent the two 

 mandibles, the two maxilla (distinctly serrated distally), the 

 hypopharynx, and the labrum. The palpi are conspicuous struc- 

 tures in all mosquitoes, and are useful as a means for classifica- 

 tion. These represent the maxillary palpi of the grasshopper 

 while the pair of flattened lobe-like organs forming the distal 

 portion of the proboscis are said to represent the labial palpi, 

 and are called the lobelia. 



Draw and label parts. 



EXERCISE 3 



INSECT MOUTHPARTS (cont.) 



E. Dipteron type (cont.). 



b. Second subtype the horsefly. While retaining the same 

 number of parts as in the mosquito, this subtype is distinctly 

 characterized by the flattened blade-like condition of these 



