A dung beetle

Behold the mighty dung beetle

An old farmer I know used to turn his pigs into the cow pasture so that they could eat the cows’ poop.

“It’s one of the best vitamin pills for piglets,” he explained. “You don’t need to give them iron shots if they eat cow pies.”

“That’s fine for the pigs,” he went on, “but for the pasture, nothing beats dung beetles. They will clean up a pasture even better than pigs will.”

Up to a point, animal manure will enrich a pasture, and make the grass grow green. But it can be too much of a good thing, not only suppressing the grass but also harboring parasites and flies. If there are not enough organisms on hand that can break down the manure (and thereby make its nutrients available to the plants that grow there) the manure will just pile up.

That happened in Australia after cattle were introduced. Native dung-eating beetles were present, but they were suited to cleaning up after marsupials such as kangaroos, not ungulates such as cows. So African cow-pie-loving beetles were brought in to do the job.

A home gardener need not take such measures, even though many of us do put manure from cows, horses and other beasts on our gardens. If the manure is too fresh, especially when applied in warm weather, flies can be a problem. So it’s best to compost it first, or till it in promptly.

In cold climates, fresh manure can be applied in fall, since freezing and thawing of the soil will open up fissures where it can gradually sink in.

It also helps to have dung beetles around, even if you don’t spread any manure at all. You’ll find dung beetles on most lists of the top helpful creatures in the garden, along with bees, earthworms, predatory wasps and mosquito-eating bats. It’s worth finding out more about what they do, especially if, for you, beetles are guilty until proven innocent.

Some beetle species, such as Japanese beetles, are garden pests, especially when displaced from their native lands, where they would be kept more in balance by natural enemies. Many are beautiful, either in appearance, such as the iridescent scarabs, or in performance, such as fireflies at night. Lady beetles are happy to gobble up the aphids on your plants. And dung beetles are happy to process dung. They bury it, consume it, and transform it into a soil amendment.

Dung beetles are found in a number of different insect families, and have diverse habits. Some eat only dung, and some eat and break down other materials as well. Some eat dung of herbivores, others that of omnivores.

Nesting habits vary too. Some burrow into a pile of manure and simply lay their eggs there, so that their larvae will have food when they hatch. Others bury eggs in the soil just under the pile. More ambitious ones tunnel deep down and lay their eggs in dung-filled brood chambers.

The most heroic are the male ball-rolling beetles that carve perfect spheres out of dung, at least twice their size and weight, roll them some distance away, and bury them in pre-excavated nests. If a female is impressed with a male’s sculpting talent and physique, she will follow him as he rolls the dung ball, sometimes riding on top as if it were a chariot.

Along the way he may encounter many obstacles. There is a scene in the extraordinary 1996 film “MicroCosmos” in which a dung beetle’s great orb gets hung up on a little stick, and he must struggle to free it, digging underneath it and shoving with all his might. At times he pauses, to get his bearings from the sun and stay on the path to his burrow. At night he’d use the moon or stars.

Danger also lurks in the form of competing males he may have to fight and defeat with his protruding horns. But if the pair makes it to the bridal chamber, the female will hatch their young from eggs inside small dung balls she makes and tends on her own.

Any gardener should be proud to host helpers such as these, along with other tillers of the soil such as earthworms and ants. Dung beetles are at work in your garden now, as they are in any natural environment, sometimes a combination of both native and introduced species. You may not see them, but you can help ensure their presence by keeping insecticides out of your yard, as they are very sensitive to toxic chemicals. They will repay you well with their labors.

Barbara Damrosch

Barbara Damrosch

Barbara Damrosch’s latest book is “The Four Season Gardener’s Cookbook.”
Barbara Damrosch

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