The Huge Confusion About Nematodes

First-time gardeners can often be quite confused about nematodes. One gardening article might include information in regard to killing nematodes, yet a garden supply outlet might sell nematodes. Why would you want to buy something that you have to kill? Nematodes are a case where fact is often stranger than fiction.

What are nematodes?

The simplest description of a nematode is that they are worms. Beyond that, the water starts getting murky. To begin with, nematodes are worms, but not all worms are nematodes. For instance, earthworms and “nightcrawlers” aren’t nematodes.

Still, nematodes are so diverse that they defy generalization, beyond saying that they are worms. Many are tiny, but not all of them are. Some of them are quite harmful while others are very beneficial, hence, the originally stated confusion.

There are estimates that between 500,000 and a million species exist, but this isn’t the biggest surprise about nematodes.

By the numbers

As can be imagined with so many species, some of which live in fresh water, some in ocean water, some in the soil, and some inside of living creatures, the total number of nematodes on Earth defies comprehension.

To give some idea of what is meant by this, a cubic yard of average garden soil can contain over a million nematodes! Let that sink in for a moment.

It is likely that there are more individual nematodes on Earth than there are all other animals combined. That includes all insects.

The good, the bad, and the ugly nematode

A large number of species of nematodes are quite beneficial. Some are decidedly not. About a third of the known species are parasites. This is both good and bad. Some species live off of plants. These can cause damage, especially to the roots of the plants. If an infestation is particularly bad, plants can suffer or die, especially if they are root crops.

Many pet owners are acquainted with two kinds of nematodes; roundworms and hookworms. These infest dogs, cats, people, and other animals. The first isn’t to be confused with ’roundworm’, the fungal infection that also infects numerous animals, including humans.

However, a large number of parasitic nematodes can infest the bodies of plant pests. This includes a huge number of insects. It is often this kind of nematodes that are sold to gardeners.

Nematode size

As can be easily imagined, some nematodes can be incredibly tiny. They would need to be in order to fit a million in a cubic yard of soil. Some aren’t little, though. A species that infests whales can grow to three feet in length, for instance.

Some of the tiniest species are among the most helpful, too. For instance, a very small nematode of certain species can sometimes eat 300,000 bacteria per hour.

More about nematodes

Nematodes infest most living creatures, including man. Nearly everyone has nematodes living within their bodies, particularly in the digestive system. Most of these cause little or no problems and few people are aware of them. Some can cause significant issues, though.

The main reason nematodes cause confusion is that they are so diverse, there are so many species and individuals, and because they can be harmful or helpful, depending on species. Hopefully, this information will clarify the issue of nematodes a little bit.


What do you think?

Written by Rex Trulove


    • Some of them are parasites, but not all of them are. Some are also helpful parasites. I’m really glad that this helped you to learn something. That is always a great thing.

    • This was inspired by a friend who asked about worms inside tomato plants. Once I figured out that they weren’t talking about hornworms, I knew that they meant nematodes.