92 MANUAL OF GENEEAL AGEICULTURE. 



the locust a mere rudiment, is longer than any other part, 

 while the paraglossa/e, large flaps in the locust, are mere 

 rudiments completely concealed by 

 the base of the labial palpi, which like 

 the glossa have been greatly elong- 

 ated. The maxillae and labial palpi 

 have been hollowed out on one side, 

 and when closely appressed to the 

 glossa form a tube for taking up iy 



liquids. Make a drawing of the head 

 of a bee, showing mouth-parts. 



True Bugs. The mouth-parts of the FlG l5 ._ SquasJl _ bug . 

 true bugs are so different from those A, head and thorax 

 of all other insects that there cannot viewed from side. B, 

 be said to be any resemblance what- mouth -parts sepa- 

 soever. Observe that when the head rated c 

 is examined from the side, Fig. 15, a slender tube is seen 

 extending from the apex of the head along the under side 

 of the body between and beyond the first pair of legs. 

 This tube is the modified labium, Fig. 15 Ib. It has a slit 

 en the under side and consists of three or four segments. 

 The slit is triangular in outline near the apex of the head; 

 it is filled by a triangular shaped labrum, Fig. 15 1, which 

 completely closes this part of the tube. Both palpi and 

 paraglossae are lacking. Contained within this tube are 

 four bristle-like structures; two of them represent the 

 greatly modified mandibles, Fig. 15 d, and two of them 

 maxillae, Fig. 15 mx. They are so changed in appearance 

 that their identity was determined only by studying their 

 development. The bristle-like mandibles and maxillae 

 have at their apices fine teeth with which they can punc- 

 ture the plant, and are usually of about the same length 

 as the tube ; but in scale insects, as the San Jose scale, the 

 tube is very short and the bristles are two or three times 

 as long as the body. Make drawing showing these parts. 



Moths and Butterflies. The mouth-parts of a moth or 

 butterfly when not in use are almost completely concealed. 

 They are rolled up into a tight spiral like a watch-spring 



