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Aphids? Spider Mites? and ants on Hindu Pan Scotch Pine #842788

Asked July 26, 2023, 8:17 PM EDT

We have about a 7 foot Hindu Pan Scotch Pine that we acquired and planted last fall (September, 2022). It wintered just fine, candled in the spring, and has been trimmed in order to maintain the characteristic "Hindu Pan" poms. Recently, we noticed a large amount of black ant activity on the trunk, branches and needle bundles. The ants are everywhere and their activity is very frenetic. I see no holes, tunnels or above ground evidence of an ant nest or debris pile. Upon closer observation, it appears that there is more than ant activity on this tree; I can see tiny "spider - like" bugs in various sizes with none of them bigger than a pin head. (See attached pictures). The ants appear to be "hunting" these bugs as I observed several of them being chased and caught. At first I thought I had an ant problem. But perhaps the ants are doing us a favor by eating the REAL scourge? Can you tell if these are aphids or spider mites? If I apply a spray for the mites and the ants then go away because their food source is gone will I have lost an opportunity to tackle the ants? They seem to be a little smaller than carpenter ants but I'm not sure. We have taken a lot of mature trees out of our lot and in the process of stump grinding and removal we encountered carpenter ants several times. I'm sure they are displaced. I do not want them to migrate into our home foundation or other wood structures so should we try to mitigate for ants even though in this case they appear to just be opportunistic feeders?

Hennepin County Minnesota

Expert Response

I am sorry it took so long to respond - I was checking with some peers who have more knowledge of the insects and pines. The insects in your photos do appear to be aphids. Below is a response from another expert regarding the aphids, ants and treatment. In addition, I included a link to a page with specific information, including treatment options ,on White Pine aphids.

Aphids are soft-bodied insects that are easily identified by the two tail pipes extending back from the abdomen. Feeding by large numbers of white pine aphids removes plant sap and disrupts food movement within the needle. This stunts the growth of branches on larger trees and may result in the death of small trees. "Honey dew", the liquid waste produced by aphids can build up and support the growth of sooty mold. This fungus gives trees a dirty appearance. The ants may be going after the honey dew. Insecticidal soap, acephate (Orthene) and malathion provide control of aphids. All of these work by direct contact with the pest so good coverage is necessary.

http://cues.cfans.umn.edu/old/Web/217WhitePineAphid.pdf
Amy J. Extension Master Gardener - HC Replied July 31, 2023, 9:37 PM EDT

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