PART U.] THE INSECTS WHICH VISIT FLOWERS. 
the ancestors of the Lepidoptera. In a former work1 I have 
sought to establish the pedigree of Lepidoptera, which has been 
foreshadowed by entomologists since last century: the subject has 
been much more thoroughly discussed by my friend Dr. A. Speyer,? 
by Mr. R. MacLachlan, and by my brother Fritz Miiller.t Apart 
from tiny midges (¢.g. the fertilisers of Arum and Aristolochia), 
and from those insects, especially beetles and bees, which occasionally 
or habitually take up their quarters for the night in flowers, 
Lepidoptera seem to be the only insects which do not confine 
their visits to flowers to the daylight: a large number of their 
species have acquired the habit of seeking their honey in the dusk 
of summer nights and evenings, free from the competition of 
other insects.2 But in our climate, summer evenings on which 
 twilight-loving and nocturnal Lepidoptera fly abundantly are not 
_ very.numerous. Though the swift and violent movements of these 
species may be due to the shortness of the period suitable for their 
flight, or to the pursuit of bats, this peculiarity is of very great 
importance to the plants they visit; for the more flowers will be 
visited in a given time, the less time that is spent on each, and the 
shorter the time that is spent in the flight from one to another. 
_ This explains how many flowers have adapted themselves specially 
_ to nocturnal insects, both by their light colours, visible in the dusk, 
__ and by their time of opening, of secreting honey, or of emitting 
| their odour. The Sphingide perform their work as fertilisers 
| peculiarly rapidly, dropping their long proboscis into a flower 
' while hovering over it, and instantly hastening away on their 
_ violent flight to another. Accordingly most nocturnal flowers have 
' adapted themselves specially to these Lepidoptera, hiding their 
' honey in such deep tubes or spurs that it is only accessible to the 
| Sphingide. 
1 Verh. des naturh. Vereins f. pr. Rheinland und Westfalen, 1869, ‘‘ Corre- 
_ spondenzblatt,” pp. 57—63. 
2 Stettiner Entom. Zeitung, 1869, PP. 202—223, 
3 J. Linn. Soc., Zool., vol. xi. p. 1 
4 Kosmos, vol. iv. pp. ” 388—390, 
> In South Brazil, according to my brother Fritz Miiller, a social wasp, Apoica 
pallida, Lep., seeks honey only by night, sitting still in its nest by day. 
