I02 INTRODUCTION 



Hypochoeris, Taraxacum) belonging to the Cichoraceae, which they visit with special 

 eagerness. Here they are protected by the marginal florets, which fold over them. 

 Small beetles also, especially species of Meligethes, remain at night in the flowers 

 or inflorescences they visit during the day, and in which, owing to the respiration of 

 these floral parts, there is doubtless a higher temperature than in the surrounding air. 



Even in the daytime the small flower-beetles just named often remain for 

 many hours in one and the same flower, and may even stop there the whole day. 

 Even larger beetles, such as the Cetoniae, linger a very long time in some flowers, 

 especially in those of Magnolias, which Delpino for that reason has described as 

 * Kaferblumen ' (Beetle-flowers) (cf. p. 15). I have repeatedly observed the earwig 

 (Forficula auricularia) staying for hours in flowers that are more or less closed, 

 e. g. in those of Tropaeolum majus, TroIIius europaeus, Arisarum vulgare, and others. 



Sometimes the stay of insects in flowers or inflorescences is against their will. 

 This is the case in ' pitfall-flowers,' such as Arum maculatum, italicum, and others. 

 Arisarum vulgare, and Aristolochia Clematitis, in the flower-traps of which numerous 

 small flies or moths are found ; also Dracunculus vulgaris, in a single spathe of which 

 Arcangeli found on one occasion 258 carrion-beetles. Insects enclosed in the flowers 

 or inflorescences of pitfall-flowers are mostly compelled to stay in their recesses by 

 hairs or bristles, which temporarily prevent egress until the anthers dehisce and the 

 guests have covered themselves with pollen. Particulars with regard to these 

 extremely remarkable flowers will be given in the sequel. 



Flowers also now and then aff"ord shelter to larval insects, which they allow 

 to develop in their interior ; as a return the adult insects effect poUination. In the 

 flowers of Crambe maritima, for example, I observed numerous Meligethes larvae, 

 which, like the beedes themselves, fed on the stamens and carpels. In spite of this 

 they are not to be regarded as injurious to Crambe. For since the beetles are here 

 the chief agents of pollination, if they and their larvae were present in smaller num- 

 bers many flowers would remain unfertilized, though it is also true that some would 

 escape injury. 



Still more interesting are the relations between Yucca and Ficus, and the moths 

 or gall-wasps, respectively, which develop within their flowers. (See Fig. 17.) 



Through the investigations and observations of W. Trelease, we know that the 

 capsule-bearing species of Yucca indigenous to North America are pollinated by 

 a moth, Pronuba Yuccasella TreL, the females of which enter the flower that is open 

 only at night, not in order to eat the pollen, but to carry it away, so as to provide 

 their off"spring with the necessary food. In order to render possible this transport 

 of pollen, the first joint of the maxillary palp is very much elongated and can be 

 rolled up, so that the Yucca moth can gather the pollen into a ball, which it holds 

 under its head and carries away to another flower. Here the female clings to two 

 filaments, introduces her ovipositor into the tissue of the pistil, and lays her eggs. 

 She then pushes the pollen-ball that she has brought with her into the funnel-shaped 

 stigma, so that pollination results. After a few days the larvae escape and are 

 nourished by the young seeds, each of them consuming from eighteen to twenty before 

 it is full grown. Pupation follows in the earth, after the larva has eaten through the 

 wall of the ovary, and has let itself down by a thread which it spins. The seeds that 

 are not consumed by the larvae then become ripe, and serve to propagate the species 



