Invertebrates
Goliath Beetle
Goliathus goliatus · also called goliath beetle, goliathus
The goliath beetle is the heavyweight champion of the insect world. Its palm-filling adults and, even more, its bird-sized grubs put it at or near the top of every list of the largest insects, and getting airborne at that size makes for one of the loudest, clumsiest flights in nature.
Overview
Goliath beetles live in the tropical rainforests of equatorial Africa, from the Congo Basin to the Guinean forests and into East Africa. The adults are active by day, climbing tree trunks to reach sap flows and gathering at fallen, fermenting fruit. The striking brown-and-white or black-and-white patterned elytra (wing-cases) vary between the several closely related species and are prized by collectors.
Size and weight
Adult goliath beetles are 6 to 11 centimetres long. The larvae are the real record-holders: a full-grown grub can weigh 100 grams or more, heavier than the adult it will become and among the heaviest of all insects. On body mass the goliath beetle is often called the largest insect alive, though longer-bodied beetles and stick insects beat it on length.
Flight
To fly, the beetle lifts only the front of its wing-cases, hinging them up like gull-wing doors, and unfolds its large hindwings from underneath. The result is a slow, heavy, droning flight — powerful enough to carry the beetle between trees but never nimble, and audible from a distance.
Males, horns, and larvae
Males carry a Y-shaped horn on the head, used to pry and flip rival males off a sap patch or a female. Females lack the horn and instead have a wedge-shaped head for digging into soil to lay eggs. The grubs develop in rotting wood and rich leaf litter, needing a lot of protein to reach their enormous size, then pupate inside a hard cell of compacted soil through the dry season before emerging as adults.
Status
The goliath beetle has not been formally assessed for conservation. It is locally common where lowland forest survives, and it is now captive-bred for the hobby, though many specimens are still collected and exported from Africa. Its longer-term prospects are tied to the fate of the Congo Basin rainforest.
Goliath Beetle: common questions
Is the goliath beetle the biggest insect in the world?
It is one of the biggest, and by some measures the heaviest, but "biggest" has several answers. The goliath beetle wins on bulk and, in the larval stage, on sheer weight — grubs of 100 grams or more rival a small bird. Adult goliath beetles are shorter than the longest Hercules and elephant beetles (whose horns add length) and much shorter than the giant stick insects and the longest beetle, the titan beetle. So the usual summary runs — goliath beetle for heaviest, titan beetle for longest body, and certain stick insects for greatest overall length.
How can something so heavy fly?
Like other scarab beetles, the goliath beetle keeps its hard outer wing-cases (elytra) mostly closed and lifts only their front edge, swinging them up and forward like gull-wing car doors, while the large membranous hindwings unfold from beneath and do all the work. The wing loading is high, so take-off is laboured and the flight is a slow, heavy, droning cruise rather than anything agile, but it is enough to move between fruiting and sap-flowing trees. In the air the beetle is loud enough to be heard well before it is seen.
What do goliath beetles eat?
The adults have a simple diet of sugary, high-energy foods — sap oozing from wounds in trees, and soft, rotting, fermenting fruit on the forest floor. The larvae are the opposite. Growing to such a size requires a lot of protein, and in the wild the grubs appear to get it from protein-rich decaying plant and animal matter in the soil and rotten wood. Hobbyists who breed goliath beetles have found the larvae grow best on protein supplements, and rearing them was difficult until that was worked out.
Can you keep a goliath beetle as a pet?
They are kept by beetle enthusiasts, and captive breeding is now established, though it is considered advanced. The adults are undemanding — warmth, humidity, fruit, and sap or a sugar jelly — but the multi-month larval stage needs carefully managed protein-rich substrate, the right temperature, and space, and a mistake usually means a small or deformed adult. Most goliath beetles in collections are still farmed or wild-collected in Africa and exported dried or live.