54 
Colour in Flowers. 
Andreae concludes that of the day-flying insects, the biologically 
higher types, i.e. those with a relatively long life in the winged 
state, and with a long direct flight, are characterised by sharp sight 
and are attracted to flowers mainly by their colour, while the bio¬ 
logically lower forms, i.e. those with a short life in the winged 
condition and a short flight, have less power of sight and are 
more dependent on smell. With these also come the specially 
adapted night-flying insects—although they include some very 
highly developed Lepidoptera such as the hawk-moths—as well as 
the whole tribe of insects comparatively little adapted to the antho- 
philous habit, for instance many of the flies, and some beetles. 
Insects which have a running rather than a flying habit, such as 
many of the beetles—whether anthophilous or not, depend, for 
obvious reasons, almost wholly on the sense of smell for discovering 
their food at a distance. The author also points out that the con¬ 
dition of bright sunlight under which brightly coloured flowers are 
mainly visited by day-flying insects, are just those which are 
favourable for enhancing the effect of colour, while the relatively 
dry air is unfavourable to the diffusion of scent. On the other 
hand the damp sultry evenings so beloved, as all lepidopterists 
know, of night-flying moths, are particularly favourable to the 
dispersal of scent. 
Of course the higher bees, notably Apis, are constantly found 
in great numbers on flowers which are not highly coloured and 
often have a strong scent, especially when great numbers of these 
are massed together. The flowers of the Lime-tree are a good 
example. On the other hand they very rarely visit highly con¬ 
spicuous double flowers where no honey is to be obtained. The 
explanation of this is simply that they are highly intelligent insects, 
which soon discover where honey is to be obtained in large quan¬ 
tities, and go back to the source of it again and again. Conversely, 
even though attracted in the first instance, they will not return to 
a brightly coloured but barren flower. Andreae’s observations bear 
out both these points, which have been somewhat neglected by 
Plateau and others. 
We may therefore regard these most recent observations as 
completely confirming the traditional view of the significance of 
colour in attracting insects to flowers; and as establishing its pre¬ 
dominant importance in the case of the most highly adapted diurnal 
anthophilous insects. 
A.G.T. 
