I think that the release of radioactive substances into the atmosphere after the Chernobyl explosion led to mutant insects of new species. There is also evidence that an underground river flows beneath Chernobyl, which could have spread this radioactivity for hundreds of kilometers underground. Since the insects are terrestrial, they reproduce underground or nearby, hence the mutation. You might not believe me, but I saw a beetle with all the bright colors of the rainbow and eyes like two billiard balls at my dacha near Novgorod. I just didn't have a camera to take a picture.