THE SWISS SPECIES OF THE GENUS HESPERIA. 45 
The Swiss species of the Genus Hesperia. 
By B. C. S. WARREN, F.E.S. 
In recent years thére have been great changes in the classification 
of the Palwarctic Hesperiidae. The defining and separating of species 
and varieties, which has been worked out in detail, both in the structural 
and superficial characteristics of the various forms, has gone far to 
simplify the task of the collector interested in the genus Hesperia. 
These changes are, by now, probably familiar to most collectors inter- 
ested in the subject, while recently Dr. Chapman has given (nt. Ree., 
vol. xxix. and xxx.) a review of Prof. Reverdin’s hévision du Genre 
Hesperia, accompanied by some useful plates. Although the separat- 
ing of the species in the genus may always be a matter of some diffi- 
culty, yet we now know that it is nothing like the impossibility it was 
so long considered to be; and with a certain amount of experience 
the European species will be found to offer no greater difficulty than 
do the closely allied species of Melitaea. One must of course except 
the case of malvae and malvoides, for it is not possible to separate these 
two species with certainty, by their superficial characteristics. It is 
easy enough with a series of the two side by side, to note certain 
differences (such as the colour of the palpi and the antenne; the 
presence or absence of the white sub-marginal spots on the upperside 
_ of the forewing) which are more prevalent in one species than the 
other, but they are, unfortunately, not constant to either, and are also 
subject to individual variation. As a general rule the locality will be 
sufficient to determine the species, but in places where the two are 
known to approach, this test will also fail. Then, again, there will 
always be the possibility of finding both species in the same locality in 
some district, from which they have not yet been recorded. There- 
fore, the identification of specimens, taken near the northern or 
eastern limits of the area inhabited by malvoides, can never be reliable, 
unless the genitalia have been examined. The mutilation of speci- 
mens is of course the principal objection to this method of identifica- 
tion ; but, when one wishes to examine the genitalia merely for the 
purpose of identification, it is not necessary to remove the body. This 
I fancy is not generally known. When dealing with fresh killed 
specimens it is quite possible, with the aid of a strong hand lens, to 
determine the species by their genitalia, without removing the body, 
or injuring the specimen in the least. Of course the greater the 
power of the lens the better, but a very high power is by no means 
essential, and when examining species in which the differences in the 
genitalia are pronounced (as they are in most of the Hesperias) it is 
not only possible, but a perfectly simple matter. The collector who 
identifies his captures of malvae and malvoides by this means, will only 
have to examine one or two specimens from each locality ; as, up to 
the present time, the two species have never been found to overlap. 
I may add here, however, that my subsequent records of the distribu- 
tion of these two species are not based on any such casual examina- 
tion; for, while I was endeavouring to ascertain the exact extent of 
their habits in the Rhone Valley and elsewhere, I examined two-thirds 
of all the specimens taken. Of course it is quite impossible to deal 
with old and dry specimens in any way except by removing the body. 
Collectors who have no previous knowledge of the genitalia of the 
Marcu 15rxn, 1920. 
