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The Dendrobium beetle (Stethopachys formosa) is one of the most destructive orchid pests. Fortunately, it has a taste for Dendrobium orchids only and rarely touches other genera. The native to Australia only beetle, has been observed in Northern NSW, Queensland and Northern Territory. Mild winter weather can help the beetles to move and survive further South. They feed practically on everything, leaves, flowers, buds, seedpods etc. As you can see (photo), the beetle is quite distinct and can be easily identified.
Females lay eggs on new growths, buds or flowers and after 10 days the larvae will emerge. The larvae will tunnel into the new shoots, causing them to rot and die. The larvae will pupate in a mass of white "waxy" material, like mealy bugs, to protect themselves from dehydration, before the adult emerges. The life cycle last only a couple of months. Prevention is the best cure. Keep the beetles of your property (orchid house). If you notice the presence of many, spray with a suitable insecticide i.e. something that kills beetles. Make sure you spray again after 2 weeks because the larvae are fully protected inside the cane. The beetle can be easily identified because of their distinct coloring; however, caching them is not easy. Young Dendrobium beetles enjoy flying and do so as you approach them, but adult beetles fly less. Normally, the beetles will curl up and drop to the ground. The only way to catch them is to place a jar under the beetle and catch it as it falls. Make sure you “fix-them-up” as soon as you catch them. |
