CHAPTER VII 
FLOWERS AND INSECTS 
83. Insects as agents of pollination. The use of insects 
as agents of pollen transfer is very extensive, and is the pre- 
vailing method of pollination among monocotyledons and 
dicotyledons. All ordinary flowers, as usually recognized, 
are related in some way to pollination by insects, but it 
must not be supposed that they are always successful in 
securing it. This mutually helpful relation between flow- 
ers and insects is a very wonderful one, and in some cases 
it has become so intimate that they cannot exist without 
each other. Flowers have been modified in every way to be 
adapted to insect visits, and insects have been variously 
adapted to flowers. 
84. Self-pollination and cross-pollination. The advantage 
of this relation to the flower is to secure pollination. The 
pollen may be transferred to the carpel of its own flower, 
or to the carpel of some other flower. The former is known 
as self -pollination, the latter as cross-pollination. In the 
case of cross-pollination the two flowers concerned may be 
upon the same plant, or upon different plants, which may 
be quite distant from one another. It would seem that 
cross-pollination is the preferred method, as flowers are so 
commonly arranged to secure it. 
85. Advantage to insects. The advantage of this relation 
to the insect is to secure food. This the flower provides 
either in the form of nectar or pollen ; and insects visiting 
flowers may be divided roughly into the two groups of 
nectar-feeding insects, represented by butterflies and moths, 
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