SEX. 
189 
should bear these large horns and have so massive a development is 
a question no one appears to have satisfactorily answered and we should 
like to see a careful inquiry made into the relative numbers of the 
sexes of these beetles either in one locality or in the offspring of definite 
parents. In these forms there is usually great variation in the actual 
amount of development of the horns or mandibles and in some species 
there are distinct types, known as teleodont (long mandibled) priodont 
(short mandibled) and mesodont (intermediate) in the one species. The 
large males of the Mutillidce are accounted for (wrongly perhaps) when 
we consider that not only must they fly and be active, but that they 
usually seize and carry off the females and that further the eggs in this 
group are not bulky or abundant. Small males offer no apparent diffi¬ 
culty since it seems natural as we have said above. Marked difference 
occurs notably in Phasmidce , in the social insects such as bees and ter¬ 
mites, in many moths, some beetles, and in some Acridiidce; it is 
probably correct to say that some preponderance in the female is 
the general rule in insects, but it is more marked for instance in 
Atractomorpha and some allied Pyrgomorplnides than in most Acridiidce , 
and the groups we mention will furnish conspicuous examples to the 
student. It is curious that this is less marked in Bhynchota and one is 
inclined to associate such sex differentiations with the more specialised 
and highly developed groups. 
An interesting sex modification is that in which the female has more 
developed mouthparts than the male, as in the Culicidce and blood¬ 
sucking Chironomidce. In these forms the female alone can suck blood. 
It is possible that this really occurs more frequently than is recorded ; 
there is, for instance, a marked difference in the size of the mouthparts 
of some Pyralids ( Lamoria , etc.). Another and a fundamental differ¬ 
ence that scarcely needs mention is the naturally longer life that 
the females enjoy ; in a very great number of cases, the completion of 
the male’s functions determines his death and this must precede the 
death of the female which has often to wait for a considerable time 
before she can successfully deposit her eggs. This is very marked for 
instance, in some species in which the female waits long periods as in 
the mango weevil ( Cryptorhynchus gravis F.), where the males die in 
August, the females living until next March to lay eggs. We believe 
this occurs in a very large number of forms and it is a factor that must 
be taken into account in estimating the relative proportions of each sex 
found. It would be interesting to know, for instance, how far this 
occurs in long-lived imagines such as butterflies ; do the males die early 
or do they wait until the females can lay eggs before mating ? 
We come then to a vast number of small modifications in one sex 
which are less directly connected with sex in the sense that they are con¬ 
nected only with courtship and the preliminaries to mating. The lumi¬ 
nosity of some insects may be cited, the European glow-worm being an 
example of a female wingless beetle which is luminous possibly as a guide 
