Gordian worm information

Life Cycle

Gordian worms, or simply gordiids, are metazoans (muticellular animals), which spend only a part of their lives as parasites, usually crickets. Adults are free-living in aquatic environments such as lakes, rivers or streams. You may also encounter them in garden ponds, your toilet or your dog's water bowl. Adults are up to a yard long but only a fraction of an inch thick. Adults mate in aquatic environments and a single female may lay as many as 10 million eggs here! Often worms are found in a large knot of worms, known as a gordian knot (click here to learn about the gordian knots and why these worms are called gordian worms).

   Click here to see a picture of an egg

Eggs will develop into larvae within about 2-4 weeks.

   Click here to see a picture of a larva

Larvae are heavy, cannot swim and will settle to the bottom of the water column, and will thus end up at the bottom of rivers and streams. Gordiid larvae will now have to find a way to get into the body of the cricket. Crickets are not found in the same environment as the gordiid larvae, so the larvae must use a transport host, in order to be transported to the cricket. Gordiid larvae do this by inching along the bottom of the stream or lake, and sooner or later will be ingested (swallowed) by another animal.

    Click here to see a movie of a how a gordiid larvae will penetrate into a     transport host (warning: this is a huge file and will take much time to download; to see this movie you must have a basic player like Quicktime) .

Once the gordiid larvae are inside most any aqatic animal, they encysts.

   Click here to see a picture of a gordiid cyst

These cysts are extremely resistant and can stay alive within the transport host for at lest one year. Many animals such as fish, snails, small crustaceans and many kinds of small insect larvae can get infected with gordiid cysts. Most of these hosts likely represent a "dead end" host for gordiid cysts, since the diet of crickets does not consist of snails and fish, since these animals are restricted to the aquatic environment.

So how do gordiid cysts get into crickets? They likely use aquatic insects. Aquatic insects, as larvae look like small "worms" and live under water. However, when they metamorphose they turn into the flying insects, which we are used to seeing. This also means that the cysts formed within these insects can be carried from the water (in the insect larvae) to the land (in the insect flies). The flies can then carry these cysts to where the crickets live. Many studies have shown that crickets are omnivores- this means they eat anything and up to one-third of what they eat is dead insects; thus, also gordiid cysts!!!

Once inside of the cricket, gordiid larvae excyst and penetrate through the gut and into the body cavity of the cricket. Here the worms grow up to adults. This growth period takes from 4-20 weeks. Once mature, the worms exit the cricket once the cricket is near water. Interestingly enough, once the worms leave their cricket hosts, they no longer feed, since their guts are degenerate and thier mothes are plugged. So, all of the energy the worms need for living in the water, mating, etc., is acquired while inside the cricket.

Click here to see worms escaping out of a cricket host (warning: this is a huge file and will take much time to download).

So, why are you finding these worms in you toilet, pet water bowl or yard? Well, sometimes an infected cricket will move away from the area in which it was infected and will carry along with it the gordiid worms. Alternatively, the flying insects containing cysts may be blown or may move (due to light pollution at night) to more populated areas. Subsequently, crickets living in those areas

Are They Dangerous to Humans?

No. Gordiid worms do not infect humans. Many reports exist of humans passing worms, but these are all likely cases in which adult worms were accidentally swallowed. Some other reports indicate that pets have also passed them. Again, accidental ingestion of adults is suspected. However, they cannot "infect" humans, pets or any other vertebrate animal.

Where Can I Find Them?

Gordiid worms are distributed throughout the world. They appear to have been found wherever anyone has seriously looked. In the United States they seem to be one of the most common metazoan animals in some aquatic systems. However, if you find an adult, consider yourself lucky. Since adults survive only a short time once they leave the crickets (about 2-4 weeks) and females tend to engage in hiding behaviors once mated, these worms can be especially difficult to collect.

If you are looking for them in streams, look for them in mating tangles near the bottom in quieter areas. Also look for the females wound around rocks in the bottom middle of the stream. Some species of gordiids will wind themselves around sticks and small branches hanging in water.