Cockroaches & Cows

by The Old Scot

What could cows and cockroaches possibly have in common? Cows are large friendly animals which give us milk and calves and other good things. Roaches, on the other hand, are nasty insects that love to live in our kitchens. They don't give us anything but the heebie-jeebies.

But different as they are, cows and cockroaches do share one thing in common: they both owe a large measure of their success in life to friendly bacteria which live inside their stomachs. It is thanks to these busy little bacteria that cows can eat grass, and cockroaches can eat almost everything they find in our houses.

In cows, the bacteria live in stomachs No. 1 and No. 2 (of a total of four). Here the germs go to work, breaking down the tough cell walls of the grass. The cows' own digestive juices can't dissolve this material, called cellulose, but the bacteria thrive on it.

They first turn the cellulose into sugar, which is their food also. But they then turn what sugar they don't need into other food products, which are the chief source of energy for the host cows.

When you see a cow chewing her cud, she is grinding up some of the undigested grass from her first stomach, in order to help the bacteria get to the cellulose.

When the grass is good, and the living is easy, the bacteria tend to multiply very rapidly-but this bothers the cow not a bit. She simply sweeps the excess into the last of her stomachs, where the bacteria are killed by her digestive juices, and they become food themselves. In fact, they are a source of vitamins, fats, and protein, which the cow needs for a balanced diet!

Science hasn't learned nearly as much about the partnership between bacteria and roaches, but it is known that they need each other. The germs apparently can't live anywhere else, and the roaches depend on the germ digestion. Without it their growth is stunted and they are weak and sickly.

Through a wonderful arrangement, when female cockroaches are ready to begin laying eggs, some bacteria move from their usual quarters to the ovaries. Here they "infect" each egg, so that each new roach will have its own supply of the little symbiotic partners.

Cows and cockroaches and germs: what a strange mixture! But they're not the only partners: germs also work cooperatively with the other grass-eaters, including horses, sheep, goats and rabbits. They even make life possible for wood-eating termites.

How did this unlikely sharing happen, anyway? Did some long-ago germ colony decide to pair up with grass-eating animals, in return for snug quarters and plenty of food delivered to the table? Or did the animal forefathers make the first approach, thinking of how nice it would be to be able to digest that nice grass?

Silly questions, aren't they? Such arrangements could never have developed, simply because they could not have gotten started. Grass-eaters can't eat grass without help, so there could not have been grass-eaters before the bacteria were already in place and doing their job. In the same way, the bacteria could not have survived without the protection they have in their hosts' stomachs.

Each partner is absolutely dependent upon the other, and has been from the beginning. This is marvelous in our eyes, because it reveals God at work in nature. Only He could design each partner for the other. Only He could create the abundant variety of life on Earth, with each species of plant and animal designed to fill its own special place and purpose.

And this is just what the Bible speaks of in Psalm 104, verses 27-28: "These wait all upon thee; that thou givest them they gather: Thou openest thine hand, they are filled with good."

Wonderful are the works of our Father and our God!


Biological Science, William Keeton, W.W. Norton & Co., NY, 1967, pp. 192-193.

The Web of Life, Part 1, John Oates, Doubleday, Garden City, NY, 1976, pp. 105-106.

Symbiosis, William Trager, Van Nostrand Reinhold Co., NY, 1970, pp. 4-13.

2011 Disciple 155x50 2011 AMG 155x50
Disciple Banner Ad