LEPIDOPTERA 171 



Some of the extra-European Sphingidae, especially tropical species, have a 

 proboscis 140-160, or even up to 250 mm. long. There are corresponding flowers 

 with corolla-tubes or spurs 6-12 cm. in length (Oenothera Missouriensis, Habenaria, 

 Gardenia, Randia, Portlandia, Exostemma, Oxyanthus, Angraecum sesquipedale). 

 Fritz Miiller found the proboscis of Macrosilia Cluentius Cr. to be about \ m. long. 



The choice of flowers by Lepidoptera is generally correlated with the length of 

 the proboscis, forms in which it is long preferring flowers with deeply seated nectar. 

 Corresponding to hawk-moths (Sphingidae) which have a greatly elongated 

 proboscis, there are special forms of flowers that are mainly or entirely adapted 

 to their visits, and for this reason Loew describes these moths as eutropous insects 

 in contrast to the other hemitropous Lepidoptera (' Blumenbesuch,' II, p. 127). The 

 majority of the hawk-moths fly about on mild summer evenings at dusk or night. 

 And as such evenings are not very common in our climate, the period of flight of these 

 and other moths is very restricted. Hermann Miiller supposes ('Fertilisation,' p. 67) 

 that either the shortness of the time when the weather is suitable for their flight, or 

 the pursuit of bats, may be the cause of the extraordinarily rapid and stormy move- 

 ments of these moths. This peculiarity of crepuscular and nocturnal Lepidoptera 

 is a decided advantage to the flowers they visit, for the amount of pollination effected 

 by every visitor in a given period of time is in proportion to the shortness of its stay 

 at each flower and the rapidity of its flight to the next. Hawk-moths demonstrate, 

 in a most marked manner, the advantage of rapid pollination for plants. Hovering 

 before the flower, they introduce their long proboscis into the corolla-tube, and after 

 a short delay hasten with stormy flight to another flower. Among nocturnal flowers, 

 therefore, most are adapted to these very Lepidoptera, having the nectar concealed 

 at the bottom of such long tubes or spurs that it is accessible to them alone 

 ('Fertilisation,' p. 67). 



While most hawk-moths visit flowers at dusk, the species of the genus Macro- 

 glossa also fly about in the daytime \ and do so in the same stormy manner as their 

 nocturnal relatives. A distinction can therefore be made between night hawk-moth 

 and day hawk-moth flowers. 



I have described in the case of Macroglossa stellatarum (' Bl. und Ins. auf. den 

 nordfries. Ins.,' p. 80) the way in which hawk-moths visit a flower. The insect 

 comes with impetuous flight in the bright sunshine of high noon to the flowers of 

 Lonicera Periclymenum, halts and hovers with trembling wings in front of the 

 entrance to the flower, and sinks the extended (22-28 mm. long) proboscis deep 

 into the corolla-tube, thus eff"ecting cross-pollination. The proboscis is withdrawn 

 as quickly as it was introduced, and the insect forthwith flies straight as an arrow 

 to another flower, there to repeat the same actions. The species of Sphinx, and 

 other genera, when visiting a flower at dusk or night behave precisely in the same 

 way as this diurnal hawk-moth. 



With what skill and persistence the Sphingidae suck deeply hidden nectar from 

 their flowers, and with what fidelity they adhere to the species once selected, thus 



^ Many Noctuidae also sometimes fly by day, e.g. Plusia gamma. Hermann Miiller ('Alpen- 

 blumen,' pp. 64 and 66) observed in the Alps several crepuscular and nocturnal moths flying by day 

 to Gymnadenia conopea and G. odoratissima. 



