394 
COLEOPTERA. 
Owing to their peculiar habits a great deal has been learnt of these 
insects since they are of extreme importance in forestry. Nearly all 
are borers in woody tissues, but few living in green tissues (the Sco- 
lytid that bores in the shoots of the common plant Vinca rosea , in the 
Western Hemisphere does not seem to occur in India though the plant 
does). Owing to the destruction they cause in forestry, the group has 
been extremely carefully studied elsewhere and the student will find 
full details in works on the forest insects of America and Europe. 
Their peculiar habits, especially in regard to sex, some being poly¬ 
gamous, some monogamous, the extreme ingenuity of their system of 
tunnelling and the fact that in some their food consists not of wood but 
of the fruiting bodies of certain fungi, which they themselves (hence 
called ambrosia beetles) cultivate with care, makes them a group of 
especial interest. They are, however, practically wholly forest insects, 
and occur almost entirely in the sub-tropical hill forest areas of India. 
No species are of agricultural importance, and the typical wood and 
bamboo borers of the plains are Bostrichidce and not Scolytidce. 
The family include monogamous species and species which are 
pofygamous ; in the first, the female prepares a bore, then goes out 
and returns with a mate and subsequently makes tunnels at right angles 
to her original bore ; each tunnel contains an egg and the male remains 
in the original tunnel. Such tunnels may be in one plane, since there 
is only one branching, and they may be contained in the bark only. In 
polygamous species, the male makes the first burrow, the females 
gathering in it and each making a tunnel from it; from these they make 
other tunnels, in each of which eggs are laid. Of these tunnels, some 
must be horizontal and some vertical and they extend into the wood since 
the narrow bark will not accommodate them. Thus in the first case, 
the borings are simple, only a coupling burrow (made by the female) 
and larval burrows at right angles (the larvae on becoming beetles bur¬ 
rowing straight out to the bark) ; in the second, they are complex and 
consist of the coupling tunnel, the mother tunnels at right angles each 
made by one female, and at right angles in another plane the egg- 
tunnels ; the system become so complex that air holes may be made 
to the bark by the mothers. In the different species the tunnels vary 
and the individual kinds are too complex to be noticed here. 
