If they no longer feel safe and supported by their current habitat, worms will migrate to another one.
Worms can leave their bin through the aeration holes — and occasionally do! For some reason, a bin’s entire population seems to make this decision en masse. They all leave at once! This mass migration is known as “worm crawl.” Once outside the bin, worms die quickly from lack of moisture. The result is rotting, stinking worms all around. That’s the “dreaded” part of the dreaded worm crawl.
Worm bins must have aeration, i.e., holes through which air circulates so the worms can breathe. Normally, worms aren’t tempted to travel out through these holes because they are happier inside. After all, it’s dark in the bin, lighter outside the bin, and worms don’t like light. It’s damp in the bin and probably drier outside the bin, and worms need moisture. Most importantly, they know there’s food inside the bin. So, the obvious question is . . .
What Causes Worm Crawl?
Worm crawl can occur when the environment is disturbed or becomes unhealthy. Worms, like all animals, have natural survival instincts. If they no longer feel safe and supported by their current habitat, worms will migrate to another one.
From a human perspective, worm crawl is most likely to happen during one of these circumstances:
1) When new worms are added to the bin
2) When a bin is moved roughly or to an undesirable location
3) When a worm bin is not maintained properly
How to Avoid Crawl When Worms Are Introduced to the Bin
A Worm’s Journey
Think about this from the worm’s point of view. One day, someone picks the worm up in a handful of worm castings and throws it into a vibrating or turning sifter. There, the poor thing is rattled loose from its castings and left hanging onto the screen for dear life. Human hands (which feel like sandpaper to a worm) pick the worm up and drop it into a bag. It is then jostled along to a location where it is turned over to you. This doesn’t feel like a stable environment to a worm.
Make the Worm Feel Safe
Stabilize your worms’ environment from the moment you take possession of them. Handle them gently. They should be given to you in a container that is moist and dark such as a paper bag or plastic cup filled loosely with damp newspaper strips. Do not make sudden or jerky movements while holding it. Avoid temperature extremes, e.g., don’t set it in your cupholder with the car’s AC blowing on it. Don’t leave them in the sun or in an enclosed car that might become too hot. Try to avoid loud noise.
The Proper Way to Introduce Worms to the Bin
When the bin is ready with bedding and food, set it in its permanent location. Pull apart the bedding and set the open container in the bin on its side, worms and all, surrounded by bedding. Put the lid on the bin and leave it. The worms will move from the container into the bedding when they are ready, probably not for a number of days. Do nothing to rush them. Don’t bother the bin except for feeding.
To keep worms from leaving your bin, create ideal living conditions. Bin shown is a 5-level Patriot Worm Tower.
First, make sure the new location is healthy for the worms. See Setting Up an Indoor Worm Bin.
Move the bin slowly and gently, similar to picking up a baby and moving her to a crib. In other words, don’t toss it, drop it, shake it, turn it upside down, or run with it.
I have found that worm crawl can be avoided if I leave the light on 24 hours a day at the new location for the first few days. Worms are more likely to remain in the dark bin because they do not like light. (Note: Light will not deter worm crawl if the bin’s conditions have become unhealthy, or if the new location is too hot, too cold, too noisy, or has no air circulation.)
How to Avoid Worm Crawl Due to Bad Bin Maintenance
As you feed your worms every 2 weeks, you should spot any developing issues in time to address them. Check that everything is moist, and contains adequate bedding and food.
Look for food remaining from the previous feeding or foul odors that may indicate there is something in the bin that should be removed.
Inspect the bottom of the bin for accumulated liquid. Worms can tolerate slight variations from optimal conditions long enough for you to correct problems. For detailed instructions on maintaining a healthy bin for worms, see How to Maintain a Healthy Worm Bin.
Mary Tynes, Master Composter, www.mastercomposter.com
TOP LEFT: Red Wiggler Image Credit: http://www.flickr.com/photos/wheatfields/3409167144/
BOTTOM RIGHT: 5-Level Patriot Worm Tower
