INSECT FERTILIZATION OF FLOWERS. 



597 



Fig. 2 



Head of Pierisrap^e (cabbage-butterfly), 

 four times enlarged. I, side view, showing the 

 proboscis coiled up. II, front view of the same. 

 Ill, side view, showing proboscis uncoiled. R, 

 proboscis ; P, labial palpi ; A, eyes ; F, antennae. 



The proboscis is usually from three to seven centimetres long, but 

 in many tropical moths it attains a length of over twenty centimetres. 

 It is by the great length of their 

 proboscis that many butterflies 

 are enabled to suck the honey 

 from flowers having very long 

 and narrow corolla-tubes, where 

 it would be quite inaccessible to 

 other insects. We need scarcely 

 say that this feature is a great 

 advantage to the butterfly order, 

 for it means that they have the 

 monopoly of the honey of flow- 

 ers with a long, tubular corol- 

 la. The honeysuckle (Lonicera 

 JPericlymenum, see Fig. 3) is a 

 good native example of a flower 

 with a tubular corolla, in which the nectary, a, is so situated as to be 

 beyond the reach of the various bees and butterflies with short pro- 

 boscides, likely to be attracted by it in the daytime. In this case the 

 honey is entirely reserved for 

 one of the evening moths 

 (Sphinx ligustri) which pos- 

 sess a proboscis of almost ex- 

 actly the same length as the 

 corolla of the flower i. e., 

 about forty millimetres. At- 

 tracted by their fragrance, 

 the insect will hover over a 

 cluster of flowers for a time. 

 Finally selecting one, it uncoils its long proboscis, thrusts it deep into 

 the innermost recesses of the corolla, and, at its leisure, sucks the sweets 

 denied to less fortunate members of its kind. 



As fertilizers the beetles are not so important as the butterflies and 

 moths. Only a small proportion pay regular visits to flowers, the 

 greater number deriving their food from quite other sources. Many 

 species which do frequent flowers only effect injury, devouring, as they 

 do, some of their most important organs e. g., the stamens or the 

 ovary. Others, however, and especially those whose small size admits 

 of their creeping into the interior of the flower, frequently promote 

 cross-fertilization, the viscid pollen adhering to the general surface of 

 their body, from which it is brushed off by the stigma of the next 

 flower they enter. Such flower-beetles as Anthrenus, Meligethes, Ma- 

 lachias, and certain smaller sorts, are extremely useful in this way. 



In other species certain parts of the tody are specially adapted for 

 obtaining food from flowers. Thus, in the crown-beetle (Cerocoma 



Fig. 3. Flower op Honeysuckle {Lonicera peridyme- 

 num), frequented by privet hawk-moth (Sphinx 

 ligustri), natural size. A, nectary; B, entrance to 

 the throat of the corolla. 



