TERRY’S TAKE: Must be spring, the nightcrawlers are out!
It hasn’t felt much like spring this spring but a sure sign it’s here is the return of the nightcrawlers. The other night following a nice rain I arrived home from work to a driveway full of plump worms scooting across the asphalt. Not only could I see them, I could smell the earthy scent that accompanies the invasion. What’s the reason for this annual event?
Researchers have come up with several reasons why crawlers come out of the soil following a good spring soaking. For many years scientists seemed to think the only reason earthworms came to the soil surface after a healthy rain was to prevent drowning in their water-filled burrows. However, earthworms are unable to drown like a human would, and they can even survive several days fully submerged in water. So now, soil experts now think earthworms surface during rain storms for migration purposes.
It gives them an opportunity to move greater distances across the soil surface than they could through the soil, they cannot do this when it is dry because of their moisture requirements.
Certain species of earthworms surface to mate, but only a few of the 4,400 existing species are known to do this, making it unlikely that mating is a primary reason for widespread surfacing.
Another explanation involves rain drop vibrations on the soil surface sounding similar to predator vibrations, like that of moles. Earthworms often come to the surface to escape moles.
Rain can set up vibrations on top of the soil like mole vibrations, similar to how earthworms move upwards and out of the way when predator vibrations are felt, they could move in a similar way for rain vibrations.
Similarly, humans create vibrations when “fiddling” for bait earthworms.
To coax worms from their burrows, fishermen run a piece of steel or a hand saw across the top of a stake, which causes a rubbing sound to occur as the stake vibrates. Myself, I just stop at the local bait shop and pick up a dozen. It’s worth the $2.50!