RonnieL wrote:
Hi Guys,
I need some help.
I took this pic recently in the Addo Park of these butterflies sitting on fresh and still wet elephant dung.
I have seen this before in the park and also outside of the park where I have seen these same butterflies sitting on cow dung and even on the damp soil where livestock have urinated or any damp soil for that matter.
I want to know what are they doing and are they able to obtain liquids and nutrients from the dung and urine?
Hi Ronnie,
My apologies; I somehow missed your item. My excuses are age and stupidity; what are yours?
You said some very nice things, but really, you were too generous by far; embarrassingly so! What I know might fill a book or two, and more than half of it is more than half wrong, What I don't know doesn't fit into all the libraries on the planet!
Your question seems simple, but it opens whole cans of worms.
Let's see...
The life histories of insects vary in their functional organisation (how they work, if you like.) However, practically all of them have two different stages combined in one way or another. Generally the first priority is to build up a working adult insect, and the second is to get the necessary materials for producing babies and if necessary, caring for them.
Let's think of a few examples. I can't go into details; there is too much!
One simple case is a moth like an emperor moth (like the Mopane "worm"). The larva eats obsessively, building up stores of protein, water, and fat. When adult it doesn't eat at all, for its "strategy"" it doesn't need to. The female simply sends out a signal for the male to follow to mate, first come, generally the only one served. He then generally dies and she lays eggs in large batches. She makes them from her bodily food stores.
That was that! It is a simple strategy and works fairly well, even if it seems brutal. But it suits the moths; they have no reason to hang about afterwards instead of dying.
Hummingbird hawk moths and butterflies tend to live longer as adults. They might last for months and generally spread their eggs more widely, some species even laying their eggs singly and widely scattered, making life hard for parasites, parasitoids, and predators. Most of them have enough bulk proteins and fats to make eggs, but need more energy for flight, energy that they get from damaged fruit, nectar and so on.
Consider mosquitoes. Some kinds like the giant mosquito Toxorhynchites spp., eat other water animals when they are larvae, in particular the larvae of other mosquitoes. They certainly deserve encouragement! Such animal food is very rich, and the adults of both genders have no need to suck blood, so they just mate, suck nectar for energy, and lay their eggs in promising pools and tree-stumps where there are likely to be munchies, such as malaria or yellow fever mosquito larvae.
Other species of mosquitoes feed mainly on detritus and microscopic creatures in the water and they do grow into functional adults, with males that don't need more proteins, but do need nectar for energy, chatting up females etc.
The same applies to the females, except that the female needs protein to build eggs. She accordingly risks her life biting you and me. They both can live for weeks in suitable conditions, each with his slightly but crucially different life history.
Butterflies now, what about those butterflies, Richfield?
Butterflies vary, but especially those that live in forests have special needs. They can easily (if they survive!) get enough food to build up the bodies of the adults, but they are famous for eating sap, dung, mud, and so on. Butterfly collectors make use of the fact to trap specimens.
You see, especially in forests, plants are short of some minerals such as sodium and chlorine that most plants don't need, but animals do. Mud often contains a job lot of minerals, and you often find mainly male butterflies sucking up the mud's moisture for its dissolved salts. Manure and urine practically certainly contain such salts, coming as they do, from large animals that had to collect the salt, sometimes from salt licks, They need to get it somehow if they want to stay functional. Nectar, juice, and sap mainly supply energy in the form of sugars, and not much mineral content. Nice, but not critical. When the males of some species have collected and concentrated a goodly supply of the necessary salts, they chat up females and offer them some of their hoarded salt supplies. A female that likes the offer will mate, which she now can afford because she is not short of the salts of animal origin that she needs to produce viable eggs.
Get the picture?
Ciao for niao,
Jon
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Interesting that the grasshopper and the caterpillars are unrelated as they were on different parts of the same roadside shrub 
