
A stag beetle with extremely long mandibles relative to body length. Beautiful metallic sheen and slender body.
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The Cyclommatus metallifer, commonly known as the Metallic Stag Beetle, is a tropical species native primarily to Sulawesi, Indonesia. Its most striking feature is its dramatically elongated mandibles — on large males, these can surpass the total body length, creating an almost sculptural silhouette. The beetle's slender frame shimmers with a vivid metallic sheen, earning it a devoted following among collectors who prize aesthetic beauty in insects. In the wild it feeds on tree sap within tropical rainforests, active mostly at night. In captivity, adults are straightforward to maintain on insect jelly, and breeding is approachable with fermented substrate or mycelium bottles. While the adult lifespan is relatively brief, many keepers find great reward in raising individuals from egg to eclosion, making this species an enduring favorite for both beginners and seasoned enthusiasts alike.
1Mandible Length Variation
Male mandibles are disproportionately long relative to body size, varying significantly between individuals. In large specimens over 70mm, mandibles alone can account for 70–80% of total body length. Check photos and measurements before purchasing to find an individual with the shape and size you prefer.
2Enclosure Size
Their extremely long mandibles can get caught on decorations, restricting movement. A simple setup with just a feeding dish and a piece of driftwood works best even in a small to medium enclosure. Choose a container with a secure, fungus-gnat-resistant lid for easier maintenance.
3Never House Males Together
Males housed together will fight aggressively, often resulting in lost mandibles or legs. A single male can cohabit with a female outside of breeding, but monitor the female for signs of stress. Separating the pair after mating typically extends the lifespan of both individuals.
4Feed Only Insect Jelly
High-protein, high-sugar insect jelly is the staple diet. Avoid fruit and sugar water as they spoil quickly and attract mites. Because long mandibles make it hard to reach into standard jelly cups, use a shallow dish or cut the jelly in half to make feeding easier.
5Temperature and Humidity
The ideal temperature range is 23–28°C; sustained temperatures above 30°C can shorten lifespan. They are also sensitive to dryness, so lightly mist the substrate about once a week to maintain moderate humidity. Indoor keeping with air conditioning, away from direct sunlight, is ideal during summer.
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Care difficulty, lifespan, size and diet — all basics covered.
6Breeding and Larval Care
For egg-laying, use a combination of soft oak logs and fermented substrate. Once the female starts chewing the log, leave her undisturbed and excavate the log after 4 to 6 weeks to collect larvae. Raise larvae in fungal mycelium bottles or fermented substrate; they take several months to about a year to reach adulthood.
7Short Adult Lifespan
Adults live only 3 to 8 months, and many individuals sold in stores are already several months post-eclosion. Always ask the seller for the eclosion date and the date feeding began so you can estimate remaining lifespan. With attentive daily care, you can make the most of every day with these remarkable beetles.