Leave it to the inquisitiveness of a three-year old to stump Dad. Most earthworms I’m aware of live, well, in the Earth. Why, then, are they the usual bait of choice for fishermen?
Seems a bit odd at first, but there are planty of wormlike creatures common in freshwater that are common prey for fish, but that’s not the real reason. The logic behind worms is as follows.
Fish detect prey largely by movement in the water, smell and by detecting electrical signals from prey muscle. Some fish will only eat live prey. To get the best effect you need something that moves and still has working muscles, so live prey is ideal. We could use insects, but they’re hard to catch, hard to keep in a tin can and won’t sink. Worms sink and are easy to capture and easy to thread through a hook so they can’t be stolen by small fish so we use worms. I’ve used freshly caught shrimp as bait, but they die on the hook fairly fast and aren’t as good. I suspect in the good ol days kids particularly couldn’t get access to anything else to use as bait.
Worms don’t work for me…
When I fish, I mainly use cockles or squid as bait. Occasionally I also use pilchards, but never worms.
The fact the I fish in the ocean may have some bearing on this.
In addition to Gaspode’s reasoning, it’s also worth noting that many fish are intimately familiar with earthworms. If you’ve ever picked your way along a sidewalk on a particularly rainy day, you know why. When the soil becomes saturated, worms make a break for the surface in search of a breatheable environment. Along rivers and on lake banks, a lot of those worms are washed into the water, where they are vulnerable targets of opportunity.
They’re free and easier to catch then crickets.