Was this an old bait? Or was it a new one?
There are different ingredients depending upon when it was manufactured. If this is something purchased within the past 4-5 years it is the newer formulation.
If that's the case the active ingredient is Indoxacarb, which is an insecticide that affects an insect's nervous system. Dogs and cats are highly resistant to the effects of this toxin.
In toxicity studies in rats, rabbits and dogs symptoms of toxicity included weakness, lethargy, drooling, incoordination, inability to stand, and a head tilt. But the doses that produced these symptoms were very, very high.
In sub-chronic toxicity studies (90 days) on dogs, oral doses of 1 to 18 mg/kg/day no clinical symptoms of toxicity were observed. Mild anemia and slightly reduced weight gains were recorded at the highest doses.
The amount that your pup may have ingested was likely no where near even the lower end of the dose. I would not expect your pup to have any symptoms from the indoxacarb ingestion.
If he ate the plastic pieces that the bait is put in those can be sharp and cause a perforation or scrapes on his intestinal lining, and if he ate enough, a blockage is possible.
You can feed him a bland diet with added fiber to help cushion sharp pieces if he ate any plastic. A homemade bland diet consists of 1/3 boiled, lean hamburger (or boiled, white skinless chicken), all fats drained off the meat, mixed with 2/3 boiled, plain white rice or well cooked pasta. Feed several small meals a day. Add 2 tablespoons of canned pumpkin (not pie filling, just pumpkin) to each meal to help increase fiber, which will help push pieces through and cushion the sharp edges as they move through.
Feed this food for several days and if he is doing well then in 2-3 days gradually start mixing in his regular diet, more at each meal. It should take about a week to get him converted back to his regular diet. Signs that things aren't going well, and he needs an immediate veterinary visit, are vomiting, a tense painful belly, lack of an appetite, a fever (more than 103.5F rectally) and lethargy. This could be related to the plastic pieces.
But if he just licked the bait he should be just fine and you are unlikely to notice any issues with him.
Please let me know if you have any further questions.