March 26, 2016

1 - PiƱon needle scale is a common New Mexico pest, but it can be fairly easily managed.

Yard and Garden March 26, 2016


Do you have a hand-out on how to deal with Pinon scale? I have read about power washing the trunk and limbs, and cleaning fallen pine needles away from base of trunk. What else should I do?

I just saw the little green bugs and want to know more about the insect's life cycle and how to interrupt it.

- Lynn H.

via University-wide Extension site


Piñon needle scale is one of the key pests of piñon pine trees. These small insects cover themselves with a protective covering (a scale) while they draw nutrients from the needles through their sucking mouth parts. These protective coverings appear as raised black dots on the needles produced by the tree the previous year. These insects can cause significant damage to the trees if they are present in large numbers over a period of several years. Each spring the female insects leave their protective covering and migrate downward toward the base of the trees to mate and deposit their egg masses. These egg masses are obvious because they are covered with a dirty gray/white yarn like material. The simplest method of managing these insects is to remove the egg masses by washing with a strong jet of water or sweeping them off the tree with a broom as you mentioned in your question. Collect and dispose of these eggs at a distance from your piñon trees so that the young scale insects cannot reinfest the tree after the eggs hatch. The female scale insects will die after they have deposited their eggs so they are not a concern. If you are reasonably thorough in removing the egg masses, you may be able to reduce the population of scale insects to a level that does not cause significant damage to the trees. You will need to repeat this physical removal of the egg masses every few years.

If you prefer to use chemical control measures, there are products on the marked labeled for management of piñon needle scale insects. For chemical control to be effective, treatment should be properly timed. To determine the appropriate time for application of chemical control frequently inspect the tree by holding a piece of dark (or light) colored construction paper under the branches. Then strike the needles sharply with your gloved hand and look for extremely small crawler insects moving around on the construction paper. When you observe the crawler insects, it is time to spray. If you delay, the small insects will settle on pine needles produced next year and produce their protective covering and make treatment much more difficult. Your local NMSU County Extension Service office can best advise you as to appropriate chemicals to use. Be sure to read, understand, and follow all label directions when using these materials.

A good publication about piñon needle scale in New Mexico is one witten by Bob Cain, formerly with NMSU Extension and NM State Forestry, and his colleagues. Your local NMSU county Extension office may have some copies of "Conifer Pests in New Mexico". You can also find it online at Piñon Needle Scale. This publication discusses many conifer pests of interest to New Mexicans; piñon needle scale is one of the first discussed.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email:, office: 505-865-7340, ext. 113.


For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms.

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