Use “Ant Trees” and Scale Hotspots to Grow Lindorus

Releasing Lindorus beetles on a mandarin tree for citrus scale control.

Releasing Lindorus beetles on a mandarin tree for citrus scale control.

Ant trees are what we call trees that ants pick out and work over more than most of the trees in the area so that they become chronic hotspots for homopteran and other pests including scale pests. Take advantage of a scale-infested ant tree by creating a barrier for the ants (see future posts about ant management) and release on the scale. They will produce Lindorus for the whole grove for the season and grow there if they don’t freeze or get disrupted by pesticides. You are unlikely to catch them in the act, but you can tell they’re working by the way they rip up the hard scale covers leaving raggedy edges where they got access to their prey. Green lacewing larvae leave similar signs but not as ragged.

Releases of Lindorus are especially valuable in a biological control programs against citrus red and yellow scale, and purple scale. You cannot afford not to do this when surplus beetles are available at deep discounts. Backgrounders about scale IPM programs are described at: IPM.ucdavis for both Red and Yellow and Purple Scale. Note that the University researchers writing these guidelines refer to Lindorus as Rhyzobius lopanthae. They are similar but distinct genera.

Red Scale on Mandarin (Photo by Dan Papacek)

Red Scale on Mandarin (Photo by Dan Papacek)

We especially appreciate Dan Papacek’s work in citrus. His excellent biocontrol tips and photos like this one can be found at bugsforbugs.com.

Florida wax scale on Indian Hawthorns could not be controlled with pesticides, but a report at U of Florida’s site includes Lindorus in an effective program. Check it out here.

Pseudaulacaspis pentagona white peach scale is also a good food for Lindorus. A classic report in the Florida Entomological Society (F.A. Collins and W. H. Whitcomb, 1975). In a more recent report in the same journal, the deleterious effect of “soft pesticides” on Lindorus. We are surprised that, “At one-half the field rate, R. lophanthae [Lindorus] had 43% mortality with insecticidal soap, 63% mortality with imidacloprid, and 46% mortality with fish oil. …the soap and oil were the least toxic of all pesticides tested.” See the full report here.

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