41 
Spring Butterflies on the Riviera. 
By J. W. Tutt, F.E.S. Read May 27th, 1897. 
I HAVE long recognised that a proper study of the time of appear- 
ance of the Lepidoptera along the Mediterranean littoral in spring 
was the only means of understanding some of the peculiarities relating 
to the time of appearance of our own species. In this way the hyber- 
nating stages of Colas edusa and C. hyale have been set at rest, 
whilst some light has been thrown on those of Pyvamers cardui and 
other butterflies. It might be urged that the climatic conditions 
prevalent along the Mediterranean littoral are so different from those 
of our own islands, that different habits might well result, even in 
the same species, when the southern races of butterflies are com- 
pared with our own. But these differences are of degree rather 
than of kind, and although frosts are rare during the winter, and thus 
many delicate species of insects exist in these southern latitudes that 
cannot live with us, yet there is a distinct winter, z.e., a resting 
period, when deciduous trees lose their leaves and herbaceous plants 
are at a standstill, when nights are cold and life is in a static condi- 
tion, which results in maintaining the hybernating habits in a more 
or less fixed manner, which we recognise in our latitudes as normal 
for the various species. Thus Aglais urtice, Lugonia polychloros, 
Polygonia c-album, and Gonepteryx rhamnt go into hybernation as 
with us ; whilst Pyvamezs atalanta, which puts off hybernation with 
us as long as possible, may be seen on any fine day throughout the 
winter enjoying the sun, and demonstrating that its torpidity is very 
different from that of Ag/azs, Eugonia, and Polygonia. Besides, it 
must be borne in mind that the difference between the summer and 
winter temperatures of Nice, Hyeres, Cannes, &c., is quite equal to, 
if not greater than, that of our own ; and if the average winter tempe- 
rature is high, the average summer temperature is much higher, and 
a difference is thus maintained. 
But if these differences result in the maintenance of similar habits 
of wintering in the various species common to the British Islands 
and the Mediterranean coasts, it produces one marked difference, 
viz. the development of regularly double or triple broods in species 
that are normally single or only partially double-brooded with us. 
This is due essentially to the fact that spring commences earlier, that 
vegetation is on the move earlier, and progresses at a more rapid rate 
than with us; whilst the higher temperature that moves the vege- 
tation so quickly, and thus provides food for lepidopterous larvee, also 
develops the eggs of Lepidoptera more quickly, promotes the more 
rapid growth of wintering larvae and the more rapid development of 
wintering pupze, whilst hybernating imagines are tempted from their 
