PEST

NAME
Orchid Beetle, Dendrobium Beetle
Stethopachys formosa

ORDER
Coleoptera

Description of the Pest
Adult beetles are small up to 12mm long and is glossy orange with black spots on the wing covers. They have chewing mouth parts and normally long black antenna. The cream coloured plump larvae is also up to 12mm long and has a slimy slug-like appearance and when pupating they are covered in a white waxy material. When disturbed the beetles drop to the ground to hide.

Appearance and Distribution of the Pest
Larvae appear from spring to summer and spread by flying, assisted by the wind or are transported on infested plant material.

     

Life Cycle
This insect has a Holometabolouslife cycle, ie. When metamorphosisis observed during the pupalstage.

Period of Activity
During the warmer months of the year.

Damage Caused
The larvae and adults feed on the epidermal layer of the new shoots, flowers and seed pods. These irregular chewed areas turn brown giving the plant an unattractive appearance. The larvae eat tunnels in the pseudobulbs or new shoots causing them top die.

     

Susceptible Plants
The pest attacks epiphytic orchids such as Dendrobium, Cymbidium and Cattleya species.

Cultural Control
The beetles may be removed by hand during the early morning, or by placing a cover under the plant to collect falling escaping beetles. The larvae are very difficult to control.

BiologicalControl
None known.

Chemical Control
Spray with a contact chemical such as Carbaryl during heavy infestations.
Note
Always read the label for registration details and direction of use prior to application of any chemicals.