FEEDING AND BREATHING 23 



past the bases of these it is passed on into the mouth 

 and gullet. 



Many sucking insects, however, depend upon liquids 

 that can be reached without the necessity of piercing any 

 plant or animal tissue. A common house-fly belongs to 

 the same order as the breeze-fly just mentioned, and 

 observant persons must notice how that familiar insect 

 wanders over lumps of sugar in a bowl, applying to their 

 surface the thickened tip of a leathery proboscis which 

 appears to be hinged on beneath the head. This is a labium, 

 corresponding closely with that of the breeze-fly, but with 

 the bi-lobed tip (labella) broader, more elaborately formed 

 and with more numerous channels. The house-fly has no 

 mandibles and its maxillae are represented only by their 

 basal regions and their palps ; the insect sucks its food on 

 exposed surfaces of many kinds. 



Another type of sucking insect whose mode of feeding 

 may often be observed is a butterfly or moth. Such a 

 graceful creature is seen to rest on a flower-head or poise 

 itself in front of a blossom, and unroll a deUcate flexible 

 " trunk," which when not in use rests coiled up in a spiral 

 beneath the head and between the prominent scaly labial 

 palps. This trunk (Fig. 9) is composed of the elongate 

 hoods or galeae of the maxillae, which, being grooved on 

 their inner aspects, are modified into flexible half-pipes, 

 provided with interlocking hooks or spines so that the pair 

 of organs can be conjoined to form a tubular sucker whose 

 tip can be stretched out to reach the nectar at the bases 

 of the floral leaves. The butterfly's maxilla has no blade 

 (lacinia) and its palp is reduced to a tiny scale-bearing 

 process, while the mandibles are altogether wanting or 

 represented only by minute vestiges. 



Thus, by means of the jaw-limbs and other feeding 

 structures, variously modified, as has been seen, in diff"erent 

 insects, the food is passed into the mouth and thence into 

 the gullet or front region of the digestive tract (Fig. 10, oe). 

 This, as well as the succeeding regions — the crop (cr) and 

 the proventriculus (pv) — is derived from the fore-gut, an 



