“My son caught what I later identified as an American toad at a picnic. I looked up instructions for care on several websites. For the first few days everything was fine. He was eating flies and ants and seemed to be getting along pretty well until I decided to change the water dish and clean up the tank a little which required handling him. Ever since that understandably traumatic experience, he won’t even look at a bug let alone try to catch it. When an ant comes near, he simply moves away. Does this represent irreparable trauma or should we wait to see if he gets comfortable again. Thanks.”
Handling amphibians can cause stress and should be avoided, but in this situation I do not believe your toad stopped eating because you held it.
Instead I have a few other ideas to offer.
First, ants may not be the best food source. While there are some types of frogs and toads that eat ants, others find them distasteful or simply won’t eat them.
You mentioned you offered flies, which are a much better alternative but may be hard to catch. Instead, if you are only keeping the toad for a short period of time and are feeding it food you catch outside from the area you caught toad, try worms. Toads love earthworms. You can place the worms in a shallow dish and if they are too long you can cut them in half. Sometimes toads will even take worms from forceps or by hand if held in front of them.
You also might consider feeding at night when the light in the room is dim. Many nocturnal amphibians, and especially true toads, may not be accustomed to eating during the day when first brought into captivity. Try feeding when the room is dark and using a flashlight to observe.
Second, if you were feeding the toad frequently for several days in a row it may simply still be full and not be interested in feeding. Toads do not need to be fed every day and a healthy individual can go for more than a week without food.
If the toad is already well-fed, try giving it a break for a couple days before offering food again, and when you do offer food try earthworms rather than ants.
Lastly, although stress from excessive handling can cause problems it is probably the stress of being in a new environment in captivity that is greater. The transition from one enclosure to another and especially from the wild to captivity can take time and frogs and toads may refuse to feed during the first few days until settled.
This is a good reason to go with captive-bred frogs and toads when you want a pet, this way you don’t have to deal with acclimating them to captivity and the potential problems that are prone to arise during this time.
If you are just keeping the toad for a few weeks then I see no problem relying on worms and other foods sourced from the area the toad was collected. But, if you plan to keep the toad long-term for the duration of its life you should probably consider also using a more reliable commercially available food source like crickets and, importantly, supplementing this food source with a high quality nutritional supplement designed for amphibians.
Also remember that if while in captivity it is in contact with other aquatic animals you keep it is best not to release it again, and if you do release the toad only do so in the same spot where it was collected.