57° 
Insects and Flowers 
very different from the broad-ended labellum of a house-fly. But it is in 
the Lepidoptera that this specialization of the mouth structure in connection 
with the nectar-feeding habit reaches its widest application and the extreme 
of its specialization. Almost no other food than nectar is taken by the whole 
great host of moths and butterflies (Lepidoptera), and throughout the order 
the mouth-parts are greatly modified, so as to form a perfect flexible, often 
very long, slender sucking proboscis (Fig. 510). (Some moths and butter- 
flies, however, take no food at all in the imago (winged) stage and these 
mostly have only rudimentary mouth-parts.) This proboscis is composed 
of the two greatly elongated maxillae with their grooved inner faces so opposed 
and locked together as to form a closed perfect tube open at its two ends, the 
tip of the proboscis and its base, the mouth (see p. 361). By means of an ex¬ 
pansion of the pharynx, to whose upper wall muscles running to the dorsal 
wall of the head are attached, an effective pumping arrangement is obtained, so 
that when the proboscis is thrust down a flower-cup into the nectary a stream 
of nectar may be drawn up into the throat. The proboscis of some moths 
is very long so as to enable them to drink from the deepest tubular corollas* 
for example that in our larger sphinx-moths, like the common tomato-worm 
moth (five-spotted sphinx), is 6 inches long (Fig. 509); in Brazil there lives a 
sphinx-moth, Macroxilia cluentius , with proboscis 8 inches long. An orchid 
grows in Madagascar with nectary 12 inches long, with almost an inch of 
nectar in the bottom, but the sphinx-moth, which almost certainly exists,, 
with a proboscis long enough to reach this sweet store has not yet been found. 
The following few examples, showing varying degrees of specialization,, 
illustrate specifically many of the already generally described adaptations, 
due to the reciprocal relation between flowers and insects. 
The simpler entomophilous flowers, such as those of the apple, cherry, wild 
rose, ranunculus, etc., brightly colored and fragrant, are mostly wide open and 
accessible to a large variety of insect visitors. They are all abundant pollen 
providers and some secrete nectar which is easily got at. But to get either 
nectar or pollen the insects have to scramble over and among the many 
crowded stamens of the center, dusting themselves well during the process, 
with pollen, which is carried on to the next flower visited and there probably 
rubbed off on to the stigma. In such simple forms the stigma of the first 
flower visited is likely to be fertilized with its own pollen by the scrambling 
visitors, if both anthers and stigma are coincidently mature (which in many 
of these flowers is not the case). But even then if the stigma is also pollinated 
by foreign pollen grains, it seems to be more strongly affected by them than 
by its own pollen. Experiments have demonstrated the superior potency 
of the foreign pollen in actually effecting fertilization. 
Open flowers of more specialization in general botanical relations, 
although of little more as concerns the particular one under discussion, are 
