STRUCTURE AND DEVELOPMENT OF INSECTS. 



13 



slightly serrated at the margins, and flattened at the base. 

 The lower pair of jaws, or maxillcB {mx.), are longer, not 

 so strong, and to each of them is attached an accessory 

 lobe, and a jointed style called a palpus or feeler. At each 



Fig. 5. — Mouth -parts of Grasshopper, separated to show position and 

 relation, a, from above the mouth; b, looking into the mouth; 

 c. from below the mouth. Ibr.. labrum, or upper lip; md., man- 

 dible or biting-iaw; mx., maxilla, or second jaw; lab, labium, 

 or und(n' lip: ^lyp., hypopharynx, or tongue; mx.p., maxillary 

 palpus. (Original.) 



side of the lower lip is another j^alpus, these palpi being 

 sensory organs. 



Sucking Moutli-parts. — In the sucking insects these 

 mouth-parts are prolonged into a tube through which the 

 juices of the food plant — or animal — are sucked. In the 

 plant-lice and other bugs the lower lip is elongated so that 

 it forms a tube, and the max ill a? and mandibles consist of 

 long hair-like bristles, or seta?, enclosed within this tube 

 (Fig. 7). The tip of this beak is rested upon the surface 

 of a leaf into which the setae are thrust, laceratino- tlie 

 tissue, and by a pumping process of the mouth the juices 

 are sucked up through the beak. The structure of the 

 mouth-parts of the various orders of sucking insects varies 



