I realize the point is moot now, but my own Google search for pain causing a fever led me to multiple answers of NO, and I know from my own medical issues that it is untrue, fever can be a rather rare response of the body to pain.
Harvester ants are the staple food source for most types of Horned Lizards or (horn toads). They provide formic acid - a necessary nutrient for horned lizards. A typical horned lizard adult may eat from 20 - 100 harvester ants a day. However, most pet stores do not supply harvester ants as feeders for horned lizards.
During warm months, catching local insects (nontoxic, of course) can provide added variety. Moths seem to be particularly relished by most toads. In the wild, they eat grubs, spiders, worms, insects, slugs, snails and other invertebrates. If your toads are wild-caught, try offering them what they eat in the wild. Adult toads should be offered three to six food items every other day. Toads under an inch in length should be offered appropriately sized food items, such as flightless fruit flies, pinhead crickets and other tiny insects.