Hi Larry,
Fireflies, milkweed bugs, monarch butterflies and their caterpillars are all toxic. A rule of thumb - if you are not sure, do not feed it. A rule of your other thumb
black & orange/red/yellow are typically a sign in nature that says, "If you eat me you will get sick or die.” Some of these insects become toxic b/c of the host plant they eat but others, like fireflies, produce the toxic chemical themselves. The chemical that produces the light, luciferin, is toxic to many reptiles and other animals, to others they may just taste bad (their colors are black and orange/red).
An interesting note: predators of fireflies in their native environment (where predator and prey have co-evolved) the predator will take its head first and drop off the back end where the "light" is located. The chemical travels thru the entire body so it is clear that b/c of this co-evolution the predator can ingest and metabolize a certain amount of the chemical but the concentration is at the "light" source.
OK, more than you wanted to know, but I always hope others are just as fascinated by this stuff as I am - even though I know you aren't LOL!
lele
here's an article on herps and fireflies
Firefly Toxicity
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0.1 veiled - Luna
0.2 green anoles Jaida & Jetta
0.1 brown anole - Jamaica
0.2 house geckos - Gaia & Tia
0.2 felines - Kyndra and Líta