This is what I came up for so far. I hope you love it and have lots of ideas on how to improve the concept.
Training.
When trying to train a beetle you may feed it a ration to increase their WIL roll by 2.
You may buy beetle treats from a village, town or city for 20 pips. Beetle treats may be used two times and automatically grant a successful training session. Beetle treats may be given to a beetle you rescued from poachers to help in the process of befriending them.
If someone in your party has a guard beetle -2 from all WIL rolls made by pet beetles your are trying to train.
If someone in your party has a pet beetle +2 to all WIL rolls made by pack beetles you are trying to train.
If you have the motherly birth sign (or something like it) -2 from your WIL roll when training Ladys & Golden Jewels. Star birth sign for Night Stalker & Snail Eater. Wheel birth sign for June & Banded Adler.
Escape.
At the end of every day roll a D6 for every untrained beetle in captivity. On a 6 the beetle escapes. After three days the beetle escapes without having to roll.
When a Night Stalker escapes it attacks you.
Unique traits.
When you catch a wild beetle roll a D10. On a 10 the beetle has a unique trait.
When you befriend a beetle that was rescued from poachers roll a D8. On an 8 the beetle has a unique trait.
Beetles with a unique trait can be sold for 1.5x their normal price.
Roll a D6.
1: Bioluminescent. Your beetle glows in the dark creating as much light as a torch. The light can not be turned off.
2: Spiritual. Your beetle can recharge one usage dot on a spell by carrying it for one week.
3: Toxic. When attacked your beetle will emit a 6" radius of poison spores. Any creature who does not exit the radius of the spores in one round gains a poisoned condition.
4: Yummy. Baddies will prioritize attacking your beetle over any other target.
5: Make something up.
6: Make something up.
Tricks.
You may spend one watch teaching your beetle a trick. Pets can learn five tricks. Guards and pack beetles can learn three tricks.
Accessory.
You can spend one full rest and a trinket to make an accessory. The accessory can only be worn by a beetle, has three usage dots and provides +2 HP. (Each beetle can only wear one accessory at a time.)
Beetle poachers.
You may stumble across beetle poachers. Roll a D4-1 to see how many beetles they have in captivity.
Roll a D10 for each beetle.
1-3: Lady.
4-5: June.
6-7: Banded Adler.
8-9: Night Stalker.
10: Snail Eater.
They will sell you a beetle at 0.75x its listed price. If you buy a beetle you must tame it in one day or it will escape.
The poachers are two rats and D4 mice.
If you rescue the beetles without buying them you may befriend them. If you have the motherly birth sign (or something like it) befriending Ladys & Golden Jewels will be easier; star for Night Stalker & Snail Eater and wheel for June & Banded Adler.
Poacher holding block.
You may discover where the poachers are holding all of there beetles and pay them a visit. The holding block has D8 (re-roll a 1 or 2) beetles. The holding block is (almost) always in a swamp and guarded by a large number of frogs.
Roll a D12 for each beetle.
1-3: Lady.
4-5: June.
6-7: Banded Adler.
8-9: Night Stalker.
10-11: Snail Eater.
12: Golden Jewel.
The pet show.
To enter a beetle they must know at least three tricks.
There are three tests. STR, DEX and WIL.
Pack beetles rolls STR checks with advantage. Guards roll DEX checks with advantage. Pets roll WIL checks with advantage. (They must roll under their own STR, DEX and WIL.)
If you can help your beetle without the wolf noticing make the check with advantage.
Failing the check by more than three scores zero points. Failing the check by less than three scores one point. Passing the check by less than three scores two points. passing the check by more than three scores four points.
In the talent round roll under 12 for each trick your beetle knows. Each success scores one point.
If you can help your beetle without the wolf noticing make the check with advantage.
Banded Adler roll all talent checks with advantage.
Bonus points.
+1 point if you caught the beetle yourself.
+1 point if you made your beetle an accessory.
+1 point if you rescued your beetle from danger.
+1 point if you ever told your beetle you love them.
+1 point if the beetle has a unique trait.
Golden Jewels +2 two points for being rare.
Snail Eaters +1 point because the wolf likes them.
Score 8 or more points to win 20 pips.
Score 11 or more points to win the spell. (Only the player who scores the highest wins the spell.)
Score 15 or more points to win proof of your bond (a blue ribbon). It grants +3 HP to your beetle and can never be broken. (Can only be worn by the beetle who won it. May be worn with an accessory.)
Stealing the spell.
The wolf may be old, but he is still a warrior and he is still a wolf. You can not fight the wolf. He would tear an entire warband to shreds. If you want to steal the spell you are going to have to be sneaky.
The wolf sits up high (perhaps on the stump of a felled oak). He is nearly deaf and he wears a pair of glasses to help his failing eyes, but his sense of smell is as strong as ever. He can communicate with any creature.