They can be a bu gger to keep on a barbless hook, so keep hold of those red Royal Mail elastic bands that come wrapped around your letters/packages.
Open them out and then using a scalpel or fine sharp scissors, cut them length ways up the middle.
You can also customise the length to suit.
Simply hook your worms then add one of the customised bands to secure them in place.
You can also use a bunch of bands together on the hook if you are short on worms, preferably having steeped a bunch of customised bands in a flavoring such as liquid bloodworm or such likes, even hook them up and dip in a glug before swinging them out.
Has worked for me on a number of species.
Hope this is of use.
The Pirate.