THIRTEEN] SECURING OUR ALLIES 
early autumn a generation of males and females is 
produced. A good observer says, “I would rather 
have a colony of hornets in my orchard when it is 
infested with slugs, than to have the same number 
of barrels of London purple sprayed on my trees.” 
They work hard all day, picking lice or slugs from 
the trees, which they devour or carry to their 
young. 
If all bees visited, indiscriminately, every sort of 
flower, it would happen that the pollen from one 
species would be carried to a wholly different 
species, where it would be useless. It is desirable 
that each kind of bee visit one particular kind of 
plant, or at least a few kinds. This proves to be 
the case, for there are many bees that never visit 
more than one sort of flowers. As the number of 
species of flowers is very great, it is not surprising 
that there are many kinds of bees. In many in- 
stances the mouth part of the bee is nicely suited to 
the flowers they select. Certain kinds, with very 
long tongues, suck nectar from long, tubular flow- 
ers, such as the yellow-flowered currant, while 
others, with short tongues, make use of shallow 
flowers. There are already reported nearly two 
thousand different species of wild bees in North 
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