Description of adult
Elephant beetles are large black scarab beetles. The male has 2 large projections on the head and another on the prothorax. They can, to some extent, move the ends of the projections together like tweezers. The beetles are 30-40 mm in length with the male being the larger.
The female lays her eggs in rotting organic matter. They hatch into small white C-shaped larvae (called white grubs) with a dark-brown head and six small legs.
The egg stage takes 3 weeks, the larval stage 29 weeks, and the pupal stage 5 weeks at about 26°C.
The beetle occurs throughout coastal Queensland.
The adults feed on pineapple, longan and lychee fruit and the bark of trees such as poinciana.
Elephant beetles can be major, though sporadic pests, especially in northern Queensland. It is especially a problem of Wai Chee, Bengal and other later maturing varieties of lychee.
Whole fruit, and sometimes whole panicles of fruit, are damaged by the beetles' chewing activity. Subsequent spoilage of undamaged fruit occurs because of staining from juice dripping from damaged fruit.
The larvae may be a problem in many species of container-grown plants where the potting mixture has a high proportion of organic matter. Organic matter attracts the females for egg laying. Larvae feed on the organic matter in the soil and, in the process, may cut off roots. Adults feed on bark of poinciana and other trees.
Beetles can be excluded with netting of a suitable mesh size (20mm mesh or less).
Manual removal from trees is sometimes undertaken. Larvae feed on rotting organic matter and heavy mulching of trees may attract beetles to lay their eggs in this material. This will increase the problem in subsequent seasons.
Entomophagous fungi probably account for a significant proportion of larvae.
There is currently no chemical control for this pest.
Chemical registrations and permits
Check the Australian Pesticides and Veterinary Medicines Authority database for chemicals registered or approved under permit to treat this pest on the target crop in your location. Always read the label and observe withholding periods.
- Last reviewed: 19 Oct 2022
- Last updated: 19 Oct 2022