I've heard that feeding just one type of insect is not good for a colony.
Feeding a single type of food is only detrimental if the food is terribly imbalanced. In an ant colony, you have many stomachs—let's call them buckets.
An article on colony-level macronutrient regulation proposes that there may be a number of macronutrients workers may need to collect independent of one another in order to grow and function, as both worker ants and the queen and developing larvae each have their own nutrient requirements. In the most simple terms, the workers require mostly carbohydrates, while the queen and developing larvae require proteins—though in reality there are many micronutrients that affect colony health.
As a particular food goes into the colony's many stomachs, or buckets, certain nutrient buckets fill up. As the colony goes about growing and foraging, other buckets become depleted. If ants only have access to an imbalanced diet (as is sometimes the case in captivity), then certain buckets will fill up and overflow, while other buckets will dry up. This explains certain situations where antkeepers report foraging ants that reject any number of foods, including some insects or sugar water they once readily accepted—the ants are simply seeking some nutrient that isn't being offered, in order to refill a bucket that has run completely dry.
byFormica Sunburst Ant Nectar is loaded with electrolytes that aim to correct this imbalance, enabling many ants in captivity to accept a wider range of foods. Over the past year of testing, I've experienced no problems feeding a single protein source, so long as it is supplemented with byFormica Sunburst Ant Nectar. The ants have never tired of either.
Edited by drtrmiller, September 3 2018 - 3:24 AM.