Rinsing blackworms is the key to keeping them for extended periods of time. I normally buy a pound every 2-3 weeks and the last ones are as fresh as the first ones consumed. They are stored in a plastic "shoebox" type container with barely enough RO or distilled water to cover them. When I used normal tap water to cover them after rinsing I noticed that I had to rinse them every day without fail as the water was cloudy. When I switched to RO I noticed that I could go 3 days until water turned cloudy. Rinsed thoroughly every other day keeps waste products produced by the worms from contaminating the squirm.
Attached is a pic of cartons in fridge with blackworms. This fridge is in my basement and is for fresh and frozen fish and newt foodstuffs. It really helps "the home life" to have a separate fridge for your live animal food products.
As far as freezing blackworms for later consumption, there is nothing wrong about that. This is how we normally buy brine shrimp, daphnia, bloodworms and scores of other tiny creatures for our pets food.
Live is always preferred but frozen is better than thrown away due to spoilage.
The unspoken issue with blackworms is leeches. Leeches are inherent with blackworms. When rinsing one can identify the leeches and take them out one at a time with a good set of long handled tweezers.
They can also be spotted clinging to the bottom of the plastic container while rinsing and removed with tweezers. Once in the tank leeches tend to congregate underneath wood resting on the bottom and under the plastic bottom piece of sponge filters. As toward weather or not leeches are detrimental to newts -I've never seen a leech attached to a newt although I have seen a 2" Smooth newt hunt down and eat a leech.
