Bamboo Mealybugs?

One way to kill noxious bamboo mealybugs on bamboo is to use a systemic insecticide. I've used Cygon (dimethoate) to control this mealybug on outdoor groves of Phyllostachys bambusoides castellon and P. nigra. It can be either sprayed onto the leaves, applied as a soil drench, or, my preference for larger bamboo (culms over 1/4" diameter), injected into the hollow space inside each culm.

Culm injection of sytemic pesticides is a method used in China to control sap sucking and some leaf chewing insects One advantage of culm injection is that there is almost no wasted pesticide released into the environment. To use this method, drill a small hole into one internode on each culm, then use a syringe to inject 0..25 ml to 1.5 ml (the amount depending on size of the culm) of full strength Cygon 2-E (23% dimethoate) into the culm.

When first using this method, test it out by injecting one or two culms to determine the appropriate dosage for your bamboo species; different bamboo species can vary in their sensitively to injected Cygon. You want enough to kill the insects, but if you inject too much pesticide, you risk killing the culm. Of the two bamboo species I have used it with, P. nigra is more sensitive than P. b. castellon to Cygon. I now use 0.25 ml for 1/2" diameter culms to 1 ml for a 2" culm for both species.

The protective effects from one injection lasts for several months.

If you don't want to use insecticides and your mealybug infested bamboo plant is in a pot, you could try dunking the entire plant under water for 12 to 24 hours. Many bamboos are native to floodplains and take tolerate immersion under floodwaters fo r several days at a time. If you can submerge the plant long enough to drown the insects, but not enough to bother the bamboo, this may clear out your mealybug infestation.