The great thing about nature study is that you can always learn something new, even from the most unobtrusive of creatures. The photograph above is of the summer azure butterfly (Celastrina neglecta), taken in a shady woods spot. It is only about 1/2 inch tall and might easily go unnoticed fluttering near the woodland floor. It can be mistaken for a flower petal if it is not moving. It has a nearly identical cousin, the spring azure (Celastrina ladon), which emerges in spring instead of summer, as its name suggests. However, in reading about this butterfly, I learned that it has an unusual lifestyle. Namely, it practices myrmecophily. Before my site is taken down for public indecency, myrmecophily refers to any mutually beneficial association between a species and ants. Normally, small caterpillars are eaten by ants. However, the caterpillar of the azure butterfly secretes a sugary liquid (honeydew) from its back which the ants consume. The ants don’t eat the caterpillars and even protect them (their food source) from other predatory insects. The caterpillars benefit by not being eaten and the ants benefit by a honeydew meal. For a photo and additional description click here.
It turns out that honeydew is produced by a variety of insects, particularly aphids and scale insects, and is fed upon by bees, ants, and even birds and lizards. Trees that are heavily infested with aphids may even drip honeydew. In Greek mythology, the infant god Zeus was fed on honeydew dripping from the manna-ash. The poet Samuel Coleridge referred to this in the last lines of his poem “Kubla Khan”:
And all who heard should see them there,
And all should cry, Beware! Beware!
His flashing eyes, his floating hair!
Weave a circle round him thrice,
And close your eyes with holy dread,
For he on honey-dew hath fed,
And drunk the milk of Paradise.
In case you were wondering about the meaning of this. Also see this post for a discussion of the related term myrmecochory.