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Dendrobium Beetle

Jeff Howes

If you do not have these beetles that originated in Queensland on your Australian native Dendrobium orchids read no further and count yourself lucky.

If you do read on ?. These orange and black beetles grow to about 10 mm long and can fly (Picture 1 and 2). In summer months, the adult beetle eats the new leaves of orchids (Picture 3). They then lay eggs in the soft, new stems and the larva a soft white maggot like grub hatches, then eats and destroy the stem and growing tip. At their worst, they will destroy all the new seasons' growth on your orchids.

Dendrobium beetle feeding    Dendrobium beetle feeding
1 (left): Dendrobium beetle; 2 (right): Dendrobium beetle feeding.
Photos: Jeff Howes

You can control by spraying an insecticide when you see them. The easier and more challenging way is to sneak up on them (there is always two of them), place your hand slowly below the leaves being eaten by the buggers and then, with your other hand try to grab them - if you miss, they will hopefully drop into your other hand as their defence is to drop to the ground when disturbed, now with a smile on your face, crush them.

Leaf Damage
3. Leaf damage caused by the Dendrobium beetle.
Photo: Jeff Howes

Control: After I finished this article, I was talking to an orchid grower about how he controls these rotten beetles and he said I should spray with 1/2 strength Carbryl  every four weeks. I will try this and see if it works for me.

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Australian Plants online - 2008
Association of Societies for Growing Australian Plants