Elephant beetle

Scientific name

Xylotrupes gideon

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.

Immature stages

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.

Life history

The egg stage takes 3 weeks, the larval stage 29 weeks, and the pupal stage 5 weeks at about 26°C.

Distribution

The beetle occurs throughout coastal Queensland.

Host range

The adults feed on pineapple, longan and lychee fruit and the bark of trees such as poinciana.

Damage

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.

Control

Cultural

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.

Biological

Entomophagous fungi probably account for a significant proportion of larvae.

Chemical

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.