INSECTS AND FLOWERS 201 



consequently visible from a considerable distance 

 in the dusk and on moonlight and starry nights. 

 After the flower-buds open, which happens 

 regularly in the evening, the perianth forms 

 a widely open bell. The dehiscence of the small 

 anthers, which are supported on thick velvety 

 filaments, takes place simultaneously with the 

 divergence of the petals, and a golden-yellow 

 adhesive pollen is to be seen in the spiral slits 

 of the anthers. Each flower is wide open for 

 one night only; by the next day the free 

 extremities of the six perianth-leaves bend 

 towards one another, causing the flower to 

 assume the form of a balloon or bladder with 

 six narrow lateral apertures. In the twilight 

 and by night, numerous small yellowish-white 

 moths (Pronuba yuccaselld), which have a metallic 

 glitter in the moonlight, flutter about the flowers 

 of the Yucca plants. The females penetrate into 

 the wide-open bells and there endeavour to 

 possess themselves of the pollen, not with a 

 view to devouring it, but that they may carry 

 it away. For this purpose they are furnished 

 with a special implement. The first joint of the 

 maxillary palp is lengthened to an extraordinary 

 extent, and its inner surface is beset with stiff 

 bristles and can be rolled up like a trunk. It 

 is used to seize the pollen, to conglomerate it 

 into a ball and afterwards to hold it. In a very 

 short time a moth collects by this means a ball of 

 pollen, which is held by the rolled-up palpi close 

 underneath the head, and resembles a great crop. 

 Laden with this lump of pollen, which is some- 

 times three times as large as its head, the moth 



