70 CONTROLLED NATURAL SELECTION 
carrying her in flight. In other species, the 
pairs unite end to end; in these cases, other 
methods encouraging the taking of the male 
are utilised, as will be shown later. But 
although it seems that when thus united, an 
enemy would chance to take male and female 
equally, in many cases, owing to the position 
in space occupied by the copulating pair, this 
is not so; for instance, in some cases the male 
clings to a grass stem or other support, whilst 
the female dangles below; a bird taking such 
a pair will strike first where the insect joins 
the grass, having learnt by experience that 
of insects, this, the head end, is the most 
vulnerable part; the bird will seize the male, 
the female becoming unjoined will be likely 
to escape. In such ways as this, by the 
assumption of a particular position on the 
part of the pair, will the taking of males rather 
than females be encouraged. 
When copulating insects are given to birds, it has been 
observed that when one has been seized, the other is 
apparently mistaken by the bird for some foreign object, 
which the bird endeavours to and does get rid of by 
rapidly shaking its head: those insects which are firmly 
joined together and only with difficulty parted will thus 
be disconnected. 
The copulating habits of the Common 
