A Terrible Truth Unleashed: The Farmed Hornworms Are Deliberately Intoxicated by an Untested Chemical Dye

Why The Hornworms Are Blue And Not Green?

Why the Hornworms Are Blue and Not Green Captive Manduca sexta larvae often appear turquoise-blue due to two factors: the absence of chlorophyll and the presence of synthetic dye in their artificial diet. In wild specimens, green coloration is produced by the accumulation of dietary chlorophyll and the binding of biliverdin to epidermal proteins. Grill and Götz (1992) demonstrated that biliverdin-binding proteins stabilize bile pigments in the cuticle, contributing to the green tone. Without plant matter in the diet, these pigments are not present, and the natural turquoise color of the hemolymph becomes visible through the translucent skin.

To standardize appearance and distinguish captive hornworms from wild ones, commercial breeders frequently add FD&C Blue No. 1 (Brilliant Blue FCF) to the artificial chow. This dye is absorbed into the cuticle and hemolymph, replacing the green tone with a uniform blue hue. The dye serves no physiological or nutritional function for the larvae. Its inclusion is purely practical, allowing visual identification of captive stock and reducing the risk of feeding wild hornworms that may contain plant-derived toxins.

Toxicologically, FD&C Blue No. 1 has an oral LD50 in rats of approximately 2000 to 3000 milligrams per kilogram of body weight (Borzelleca et al., 1990). While considered low-risk in mammals, its metabolic fate in reptiles has not been studied. The average dye content in a single large hornworm is estimated at 5 milligrams.

For a chameleon weighing 150 grams, the estimated LD50 range would be 300 to 450 milligrams. Based on this, the number of hornworms required to reach LD50 thresholds is as follows: 

At the low end (300 mg), approximately 60 hornworms 

At the high end (450 mg), approximately 90 hornworms

Subclinical concern thresholds can be estimated at 10 percent of LD50: 30 to 45 milligrams of dye Equivalent to 6 to 9 hornworms

Feeding a chameleon 6 to 9 dyed hornworms in a short period may approach subclinical concern thresholds, especially if repeated weekly. Given the lack of reptile-specific metabolic data, this exposure could plausibly affect hepatic or renal function over time.

FD&C Blue No. 1 is not nutritionally necessary for hornworms and has not been evaluated for safety in chameleons. While acute toxicity is unlikely at typical feeding levels, cumulative exposure may pose risks. Until reptile-specific toxicological studies are available, dyed hornworms should be used sparingly, and preference should be given to larvae raised on natural plant diets.

It must be said clearly: feeding dyed hornworms to chameleons is not just unnecessary—it is irresponsible. If 6 to 9 worms may approach toxic thresholds, then even 3 to 5 could already trigger mild, invisible reactions. These are not theoretical risks. They are plausible, measurable, and entirely avoidable. The dye serves no nutritional purpose and introduces a chemical burden that has never been studied for reptile safety. Would you feed your child a substance that was never tested for their biology just because it looks neat? Then why risk it with your animals? Stop feeding dyed hornworms. There is no benefit, and there is real danger.