Anglers refer to chrysalids, the stage maggots pass through prior to hatching as flies, as CASTERS.
http://www.coarse-fisherman.co.uk/tuition/basics/bait.shtml
Anglers refer to chrysalids, the stage maggots pass through prior to hatching as flies, as CASTERS. CASTERS are a fine bait for targeting larger fish. They can be hooked in the same way as maggots, or the hook can be buried inside the caster, when the fish are not feeding boldly.
chrysalid = chrysalis = pupa of a moth or butterfly enclosed in a cocoon
pupa = The nonfeeding stage between the larva and adult in the metamorphosis of holometabolous insects, during which the larva typically undergoes complete transformation within a protective cocoon or hardened case
maggot=The legless, soft-bodied, wormlike larva housefly and blowfly or of any of various flies of the order Diptera, often found in decaying matter
http://www.tenchfishers.net/toptips.htm
The darkest most buoyant casters should be selected for the hookbait to assist in counterbalancing the weight of the hook. It's useful to skim off any floaters and put them in a separate container to develop.
http://freespace.virgin.net/g.marsden/Beginners/beginners6.h...
Baits / Casters are older maggots that have turned into the chrysalis stage of their life cycle and have become inanimate though still alive. They are almost as popular as maggots but cost a little more. Bury the hook in them, or hook as a maggot.
www.fishingmagic.com
... casters, dead maggots, etc, can give your mix an edge. Certainly mixing in samples.., making your hookbait look ...
www.tacklebargains.co.uk
hungry fish actively search the water for your hookbait. ... hooks, with baits like stewed wheat, corn, maggots and casters. ...
www.anglerscircle.co.uk
I started with a deep rig fishing a couple of inches from the bottom with double caster. ...
www.baymaltonanglingclub.org.uk
... Float fishing with double caster hookbait tempted this fine looking specimen and was the highlight of a superb days fishing on the water.