194 
INSECTS. 
years; a North American species, Cicada septemdecim, being known as the 
seventeen-year locust, since that period is the interval between one generation 
of winged insects and the next. They inhabit chiefly the warmer regions of 
the earth, of the four or five hundred species known, not more than eighteen 
being found in Europe, and these mainly in its southern parts. The song 
of the cicadas, which has been celebrated from very early times, is only 
produced by the male insects. “ Happy ” writes a Greek poet, “ are the 
cicadas’ lives, for they all have voiceless wives.” The females are necessarily 
silent, since they are without the special apparatus for producing sound 
distinctive of the males. The two scaly plates which in the latter cover 
the under side of the base of the abdomen, are not, as sometimes supposed, the 
sound - producing organs. But if one of them be stripped ofl* there will be 
disclosed a cavity, divided by an oblique horny ridge into two portions, 
the inner one somewhat irregular in shape, and exhibiting tense glistening 
membranes in its walls, while the outer portion is narrow, and opens by a 
narrow mouth towards the side. Hidden in the wall of the latter chamber lies 
the membrane which is the chief organ concerned in the production of sound. 
These membranes are set in vibration by the contraction and relaxation of a pair of 
strong muscles attached to their inner faces and lying inside the body. The other 
membranes in their neighbourhood seem to serve the purpose only of modulating 
the sound. The cicadas figured are two of the commoner species from South 
Europe. Both live on ash trees, although Cicada orni selects by preference the 
manna ash. The specimen with its under side exposed may be easily recognised as 
a male, on account of the two plates, or opercula, covering the cavities in which the 
sound-apparatus is lodged. 
The lantern-flies and other insects included in the family Fulgoridce are 
characterised by never having more than two ocelli, these being placed, one on 
each side, near the inner margin of the compound eyes. The latter are not large, 
and below them are inserted the short and inconspicuous antennse. The front, 
vertex, and sides of the head are usually separated from one another by sharp 
crests, and the head itself is in some cases greatly prolonged in front. The fore¬ 
wings are either similar in texture to the hind-pair, or else somewhat harder and 
more leathery. The Chinese lantern-fly ( Hotinus candelarius), so widely distri¬ 
buted in Asia, is one of the best known; the common names said to be given to it 
in China being very suggestive of its luminosity, although so far there is no trust¬ 
worthy evidence to show that it possesses any such property. Lantern-flies are 
nearly all prettily coloured; and of the other insects belonging to the same family 
there are some, like those of the genus Flata, rivalling in the delicacy of their 
colours the most beautiful butterflies or flowers; while others, as in the genus 
Flatoides, exhibit that curious mixture of grey and black, which, in combination 
with the flattened form of their bodies, gives them the most astonishing resemblance 
to lichen-coverecl bark. The species of Flata and other genera are remarkable 
also for their white tufted tails of wax, which are found more especially in the 
larvse, but are often present also in the winged insects. These insects do not stir 
far from their food-plant, on which they may be seen both in the larval and adult 
state, clustered together in large numbers, somewhat after the manner of plant-lice. 
