1046 



Rural School Leaflet. 



Fig. 16. — Honey-bee. A, 

 head of honey-bee show- 

 ing mouih-parts extend- 

 ed; B, maxillae and la- 

 bium enlarged 



for the students of insects to recognize the group to which any particular 

 insect belongs by a study of its mouth-parts alone. Bees and wasps 

 have one type; the two-winged flies, as the mosquitoe, horse-fly, and 

 house-fly, another; the true bugs, as the cicada, stink-bug, and squash- 

 bug, another, and the moths and butterflies 

 still another. 



Bees and wasps. — The mouth-parts of these 

 insects are usually stated to be of the sucking 

 type; they are in reality a combination of the 

 two. Mandibles, Fig. 16 md, with sharp cut- 

 ting edges are usually present and fitted for 

 biting, the upper lip is small and indisti.nct, the 

 maxillae and labium. Fig. 16 A, have been 

 greatly elongated and find their greatest de- 

 velopment in the honey-bee. If the maxillae, 

 Fig. 16 mx, of the honey-bee are compared 

 with those of the locust, it is seen that the 

 lacinia is wanting and the maxillary palpus. Fig. 16 mp, is reduced 

 to a mere tubercle. The greatest modification is found in the labium; 

 the glossa. Fig. 16 g, in the locust a mere rudiment, is longer than any 

 other part, while the paraglossae, large flaps in the locust, are mere 

 rudiments completely concealed by the base of the labial palpi, which 

 like the glossa have been greatly elongated 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 liquids. 



True bugs. — The mouth-parts of the true bugs 

 are so different from those of all other insects that 

 there cannot be said to be any resemblance what- 

 soever. When the head is examined from the side, 

 Fig. 17, 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. 17 lb. It has ^ 



a slit on the under side and consists of three or ^^^- ii— Squash-bug. 



£ ^ -T-u ^■^ ■ ^ • 1 • ^1- ^' ^'^^^ ^"^ thorax 



tour segments. Ihe slit is triangular m outline near viewed from side. B, 

 the apex of the head ; it is filled by a triangular mouth-parts sepa- 

 shaped labrum. Fig. 17 1, which completely closes 

 this part of the tube. Both palpi and paraglossae are wanting. Con- 

 tained within this tube are four bristle-like structures; two of them 

 represent the greatly modified mandibles, Fig. 17 d, and two of them 

 maxillae, Fig. 17 mx. They are so changed in appearance that their 



