Quick answer: keep flower beetles in a ventilated enclosure with a close-fitting mesh lid, over a bed at least 10 to 15cm deep of flake soil mixed with leaf litter and rotten wood, which is where the females lay and what the grubs eat. Feed the adults soft, ripe fruit and beetle jelly, give them bark to climb, and keep the African species at 22 to 26°C, with a heat mat or cable on the tub's side, on a thermostat, if the room is cooler.
What Are Flower Beetles?
The beetles the hobby calls flower beetles are the flower chafers, the scarab subfamily Cetoniinae: about 3,600 species in 510 genera worldwide, by the Australian Museum's count. The adults feed mostly at flowers, sap runs and ripe fruit, with weak jaws tucked away under the front of the head. They also fly unusually: where most beetles lift their hard wing cases clear, a flower chafer keeps them shut, or nearly so, and unfolds its flight wings from underneath. The grubs are fat, white and C-shaped and live in rotting plant matter, from tree hollows to compost heaps. Britain has its own, the best known being the metallic green rose chafer, whose grubs the RHS counts as beneficial in compost heaps.
Flower Beetles Kept as Pets
I rear several kinds of flower beetle from grubs, and the care here is built around the four I keep or sell:
- Sun beetle (Pachnoda marginata). Yellow patched with chestnut brown, 20 to 25mm long, and the usual first beetle. Its grubs are sold as reptile livefood, as fruit beetle or Pachnoda grubs, and my own adults were reared here from grubs.
- African fruit beetle (Pachnoda fissipunctum). The sun beetle's close relative, kept the same way, with a dark marking on its back whose pale patches often read as a small skull. My African fruit beetle colony comes from several bloodlines, bought from pet shops, online sellers and the IHS reptile show in Blackpool.
- Derby's flower beetle (Dicronorhina derbyana). Metallic green with cream stripes, up to about 50mm long, from eastern and southern Africa, the males bearing a flat horn shaped like a T. I list it as the Stripy Flower Beetle.
- Sapphire flower beetle (Protaetia speciosa cyanochlora). Dark metallic blue, from the Zagros range in western Iran, and the only one of the four that needs no heat mat.
The hobby keeps many more; ask the breeder for the temperature, because origin decides it. My guide to the best pet beetles for beginners compares the ones I keep or sell.
Setting Up a Flower Beetle Enclosure
A single enclosure serves the whole colony: beetles above, grubs below in the bed.
- Size. About 30cm a side suits a small group of the 20 to 25mm Pachnoda; Derby's flower beetle wants a bigger, deeper bed. For scale, in a 2023 study a Berkshire wildlife park kept its sun beetle colony, which ranged from 25 to 57 beetles, in a glass tank 60cm long, 30cm wide and 40cm high over a 13cm bed.
- A close-fitting mesh lid. The adults fly readily, so the lid is the security, not the walls, and mesh keeps the air moving.
- Something to climb. A 2014 study found sun beetles have no adhesive pads on their feet and can barely walk on a glass-smooth surface, gripping instead with claws that catch on rough surfaces. Bark flats, cork and twigs give them footing, and something to grab if one lands on its back, as an upturned beetle on a bare floor can exhaust itself.
The bed is the grubs' food
Give it a depth of at least 10 to 15cm; breeders' laying beds run to 20cm. Use flake soil, with crushed hardwood leaves and soft, crumbling rotten wood worked through, and pack the lower layers down hard, because the females lay into that firm base. The grubs eat all of it, so leave out coir, which holds moisture but isn't food, and pine or any other softwood. Freeze each new bag at -18°C or colder for at least a week against mites, then air it for a few days and check it feels cool, since a bag still fermenting can warm itself.
Temperature and Humidity
The African species do best at 22 to 26°C and manage 20 to 28°C, and Derby's flower beetle sits in a similar range. Over the heating season an English home averages about 19°C, below that range, so from autumn to spring give the African species extra warmth from a heat mat or heat cable on a thermostat, fixed to the side of the tub and never underneath, where it would heat the floor the grubs cannot escape. I run heat cable along the back of my racking shelves on thermostats, cheaper than a mat per tub once there are many tubs. The Sapphire flower beetle is happy at room temperature with no heat mat, and my Sapphire flower beetle care guide covers the argument over giving it a cool winter rest.
Keep the Pachnoda at 50 to 70 per cent humidity with a light mist every few days. The bed should clump when squeezed without dripping, and a lid that fogs means the tub needs more air.
Feeding Adult Flower Beetles
Give the adults soft, ripe fruit. Banana is a staple in laboratories and zoos, and apple, pear, mango and orange all go down well; cut firmer fruit open, since their jaws are weak. Replace fruit every two days or so, before it sours and draws mould and mites. Beetle jelly pots are the easy standby, pressed into the bed and lifted out after a couple of days, before they mould. Flower beetles need no live food.
Grubs, Breeding and the Life Cycle
Keep adults of both sexes together on a good bed and the two Pachnoda breed with little help. Females lay into the firm lower layer, the grubs eat their way through the bed, and a full-grown grub builds a cocoon from the bed around itself to pupate in. Flower beetle grubs share a bed happily, unlike stag beetle grubs, though keepers report that crowding gives smaller adults. Keepers' figures for the sun beetle run from three to six months, egg to adult; breeders give Derby's flower beetle eight or nine months to about a year, and the Sapphire flower beetle needs about a year. Resist digging to check, and leave any cocoon you see alone. The grub below is one of my own, a Protaetia formosana.
My guide to the flower beetle life cycle takes each stage in turn, the African fruit beetle care guide sets out the Pachnoda routine in full, and keeping beetle larvae covers grub stages L1 to L3, tub sizes and bed changes.
Handling Flower Beetles
Adult flower beetles are safe to hold, with mouthparts made for fruit and sap rather than biting. Their hooked claws grip skin, and keepers report a prickle or the odd scratch. Let a beetle walk onto your hand, and to put it back, hold bark or cork against its feet so it climbs across. Handle them low over the tub with the windows shut. Big grubs can nip, so move grubs with a spoon.
Springtails Yes, Isopods No
Springtails are the cleanup crew to choose. They graze mould and leftovers, and one beetle keeper reports they bother nothing in a beetle tank unless their numbers boom; a warmth-loving culture such as orange springtails, which build fastest at 21 to 27°C, suits a tropical beetle tub. Keep isopod colonies out of a breeding bed: they compete with the grubs for food, and one keeper reported isopods eating every beetle egg in a container.
Buying Adults or Grubs
Adults are the quick way in: beetles to watch from day one and, with both sexes, the whole cycle. Grubs are sold by stage: L1 is freshly hatched and the longest wait, L3 the last stage before the cocoon and the quickest to an adult. My sun beetle grubs come from a variety of breeders, with new blood added at least once a year for genetic diversity.
Whatever is ready, adults or grubs, is on the beetles for sale page. Livestock goes out Monday to Thursday by Royal Mail Tracked 24, or Special Delivery Guaranteed by 1pm if you choose Next Day at checkout, and my live arrival guarantee covers every livestock order.
Never Let a Flower Beetle Go
None of the four beetles above is native to Britain. In England and Wales, section 14 of the Wildlife and Countryside Act 1981 makes it an offence to release, or allow to escape into the wild, any animal of a kind not ordinarily resident in and not a regular visitor to Great Britain in a wild state; Scotland's version covers releasing an animal, or letting one escape, outwith its native range. The defence is having taken all reasonable steps and exercised all due diligence, so keep the lid on, pass spare beetles and grubs to other keepers, and never tip old bedding that could hold eggs or grubs onto a compost heap.
Frequently Asked Questions
How long do flower beetles live?
Adults of the kinds here live a few months to most of a year: sun beetles are usually quoted at about five months, Dublin Zoo gives five to ten, and a UK college zoo study recorded some past ten.
What do flower beetles eat?
Wild adults feed on pollen, nectar, tree sap and ripe fruit; kept adults do well on soft fruit and beetle jelly. Grubs feed on the bed itself: rotting leaves and wood, or flake soil.
Do flower beetles fly?
Yes, and readily. They fly with their wing cases almost closed, the flight wings unfolding from underneath, so a close-fitting mesh lid is essential.
Do flower beetles bite?
Adults, no. Their mouthparts are too weak, built for soft fruit, pollen and sap, so the worst an adult does is prickle with its claws; a big grub can give a nip.
Are flower beetle grubs the chafer grubs that damage lawns?
No. The RHS names garden chafer and Welsh chafer grubs as the lawn pests, eating grass roots under the turf. Flower chafer grubs, such as the rose chafer's, feed on rotting plant matter in compost heaps and do not normally harm plants.
How do you tell male and female flower beetles apart?
It depends on the species. A male sun beetle has a groove running lengthwise down the centre of his belly, where a female is smoothly rounded, and a male Derby's flower beetle has a flat, T-shaped horn on his head. I have found no published sexing character for the Sapphire flower beetle, so start that one with a group of five or six.
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