Too large and too tough-bodied for most crested geckos, which have comparatively small mouths and delicate jaws — a real choking and injury risk, and their aggressive bite can injure an unprepared gecko. Skip these for this species regardless of the gecko's age.

The hard chitin exoskeleton is difficult for a crested gecko to digest, and the poor Ca:P ratio offers little nutritional benefit over a complete CGD diet. Generally skipped in favour of softer-bodied feeders if offering live insects at all.

Far too fatty for a species this small — 22% fat content can contribute quickly to obesity in a gecko that typically weighs only 35–65g as an adult. Skip entirely; there's no good reason to offer these to a crested gecko.

High acidity can irritate the digestive tract and isn't part of this species' natural diet. Skip oranges, lemons, limes, and grapefruit entirely.

Contains persin, a fungicidal toxin considered dangerous to many animals. Every part of the plant — fruit, skin, pit, and leaves — should be kept well away from the enclosure.

Lethal to reptiles generally — fireflies produce lucibufagins, defensive steroid toxins that cause rapid death if ingested. There is no safe amount. Never feed any wild-caught bioluminescent insect.

Any insect from your garden or an outdoor space carries pesticide residue, herbicide contamination, and parasite risk with no reliable way to test or clean it. Only feed captive-bred insects from a reputable supplier if offering live feeders at all.

Widely marketed as "reptile safe" because it was assessed for dogs and cats, not reptiles — it appears on the Reptiles Magazine toxic plant list. Despite being an extremely common, hardy, humidity-loving vine that would otherwise suit an arboreal enclosure well, it should be avoided given how much time a crested gecko spends investigating and resting on foliage.

Contains calcium oxalate crystals that irritate on contact — avoid, despite superficially similar growth habit and humidity needs to pothos. Use a genuinely safe climbing vine instead, such as pothos-alternative Ficus pumila (creeping fig) or a silk plant.

Also contains calcium oxalate crystals and appears on multiple reptile toxic-plant lists despite superficial resemblance to safer climbing vines. Avoid, especially given how much foliage-time this species spends.

Contains calcium oxalate crystals and is toxic if grazed on. Its humidity preference would otherwise suit this enclosure, but toxicity rules it out entirely.

On the Reptiles Magazine toxic plant list. Contains triterpenoid saponins and falcarinol, both toxic on ingestion, despite being a common, hardy climbing vine that would otherwise suit an arboreal setup.

Extremely toxic to virtually all animals — contains cardiac glycosides that cause heart failure even in small doses. Keep entirely away from any reptile enclosure.

One of the most toxic plants to animals generally. Every part contains cycasin, causing severe liver failure. Never place near a reptile enclosure.

The entire genus produces a milky latex sap causing severe burns and irritation on contact, and is toxic if grazed. Also poorly suited to humid conditions regardless of toxicity. No Euphorbia species should be used.