DISPERSION OF POLLEN BY ANIMALS, 163 



their own homes which are furnished with safe retreats, and to these they with- 

 draw at dusk and in bad weather, and butterflies, for the most part, are afraid 

 to seek the interior of flower-bells or funnels for any length of residence partly 

 because of their relatively large wings, which are liable to be injured in such 

 confined quarters, and partly because in case of danger a rapid escape from the 

 inside of a flower would be scarcely possible. Only beetles, flies, and Hymenoptera 

 of the genera Meligethes, Melanostoma, Empis, Andrena, Cilissa, and Halictus 

 need be mentioned; they are essentially nomadic in their habits, not possessing 

 homes of their own or any settled night-quarters, but are satisfied with second-rate 

 shelter, and usually pass the night wherever they have spent the day. If there 

 should happen to be flowers there which ofifer agreeable food in addition to a warm 

 retreat so much the better. Doubtless it is for these reasons that the honey-bearing 

 blossoms of the Bell-flowers (Campanula) and the Foxglove, the interiors of which 

 after sundown have a somewhat higher temperature than the environment (c/. 

 vol. i. p. 500), are especially favourite shelters on cold nights. The large capitula of 

 Crepis grandiflora, and of several other Composites whose outer ligulate flowers 

 close in the evening, are also sought after by small beetles (Cryptocephalus violaceus, 

 Meligethes ceneus) and little dark-coloured bees (Panurgus ursinus) to serve as 

 nocturnal refuges, because a higher temperature prevails at night inside the closed 

 capitula than outside. At sunrise they abandon their night-quarters, and in doing 

 so probably — in some cases inevitably — brush off" some of the pollen which they 

 carry away and take with them on subsequent visits to other flowers. 



Sometimes insects remain in comfortable quarters of the kind not only during 

 the night but also during the day, and even for several days. When once the small 

 beetles of the genera Anthohiurti, Dasytes, and Meligethes have ensconced themselves 

 in the interior of the flowers of Magnolias or Gentians (Magnolia ohovata, M. 

 Yulan, Gentiana acaulis, G. ciliata, G. Pnewmonanthe, &c.), they do not abandon 

 this comfortable home till the third day. This is also true of the rose-chafers 

 (Cetonia), which have a preference for the flowers of Magnolia grandiflora. They 

 usually force themselves into the youngest flowers which are only just open and 

 take their fill of the sweet juices exuding on and between the stigmas. Later on 

 they devour also some of the pollen as it is liberated from the anthers and drops 

 upon the petals. When the Magnolia-flowers open under a bright mid-day sun, the 

 Cetonias keep still and warm themselves in the sunshine, and when evening comes, 

 and the upper petals close up, they have no inducement to leave the quarters they 

 have chosen, for the temperature rises in the inclosed space during the night from 

 five to ten degrees Centigrade above the temperature outside, and, besides, the Cetonias 

 are here completely sheltered from the attacks of nocturnal animals. Thus they 

 stay in the flowers until the petals fall off" and leave them exposed to the air. The 

 flowers of the Opium Poppy (Papaver somniferum) are likewise sought out by flies and 

 beetles as soon as they open, and are not deserted until the petals drop. The sojourn 

 is, however, much shorter than in the case of Magnolia-flowers owing to the fact 

 that the Poppy only closes once for the night and loses its petals the very next day. 



