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Darwin, Charles, 1809-1882

"Effects of Cross and Self Fertilisation in the Vegetable Kingdom"

I then
went to a female plant some yards off, and saw in the course of fifteen
minutes three of these moths alight on the stigmas. Lepidoptera are
probably often induced to frequent the flowers of the same species,
whenever these are provided with a long and narrow nectary, as in this
case other insects cannot suck the nectar, which will thus be preserved
for those having an elongated proboscis. No doubt the Yucca moth visits
only the flowers whence its name is derived, for a most wonderful
instinct guides this moth to place pollen on the stigma, so that the
ovules may be developed on which the larvae feed. (11/4. Described by
Mr. Riley in the 'American Naturalist' volume 7 October 1873.)With
respect to Coleoptera, I have seen Meligethes covered with pollen flying
from flower to flower of the same species; and this must often occur,
as, according to M. Brisout, 'many of the species affect only one kind
of plant." (11/5. As quoted in 'American Nat.' May 1873 page 270.)
It must not be supposed from these several statements that insects
strictly confine their visits to the same species. They often visit
other species when only a few plants of the same kind grow near
together. In a flower-garden containing some plants of Oenothera, the
pollen of which can easily be recognised, I found not only single grains
but masses of it within many flowers of Mimulus, Digitalis, Antirrhinum,
and Linaria.


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