Insect identification in Michigan conifers - Ask Extension
The conifers that I use in my walking sticks are balsam and spruce. Please send any publications that will assist me in identifying the insects that b...
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Insect identification in Michigan conifers #894225
Asked March 12, 2025, 2:01 PM EDT
The conifers that I use in my walking sticks are balsam and spruce. Please send any publications that will assist me in identifying the insects that burrow and make the galleries in these species in northern Michigan.
Dickinson County Michigan
Expert Response
A good reference to get you started would be Garden Insects of North America by Whitney Cranshaw and David Shetlar (ISBN:<personal data hidden>442). If you are looking for something more specific and detailed, I would recommend Insects that Feed on Trees and Shrubs by Warren Johnson and Howard Lyon (ISBN: <personal data hidden>25). The Christmas Tree Pest Manual from MSU Extension (https://www.canr.msu.edu/resources/christmas_tree_pest_manual_e2676) is a great resource for diagnosing damage to living trees and it has a good list of potential candidates for wood injury. However, is not written for the purpose of identifying damage in dead or harvested timber and I am not sure how useful it will prove for you purposes.
If you are looking for free resources that are available online, there are not many options that cover our area (Eastern North America). However, there are some good resources for other regions and the general types of insects are the same. Just keep in mind that many of the species mentioned will not be found in Michigan. Here is one example:
Field Guide to Insects and Diseases of Arizona and New Mexico Forests: https://nmdeptag.nmsu.edu/media/pdf/field-guide-insects-and-diseases-of-AZ-and-NM-forests.pdf
For closer to Michigan, you might find this article about insects in firewood from Purdue Extension, helpful: https://extension.entm.purdue.edu/publications/E-67/E-67.html
In a nutshell, larger tunnels (>1/8") that meander just under the bark, are usually from flat-headed borers (Buprestidae). Larger tunnels that penetrate into the sapwood/heartwood, are usually from round-headed borers (Cerambycidae). Smaller tunnels and galleries (<1/16") are from bark beetles or ambrosia beetles (Scolytinae). All of those previously listed are beetles (Coleoptera). There are some Lepidoptera (moths) and Diptera (flies) that also bore in the wood of conifers, so if you see something that doesn't seem to fit with beetle damage, then it may be something else that did the damage. The Christmas Tree Pest Manual from MSU Extension (https://www.canr.msu.edu/resources/christmas_tree_pest_manual_e2676) could help you determine if the damage was done by one of the moth pests of conifers in Michigan.
If you are looking for free resources that are available online, there are not many options that cover our area (Eastern North America). However, there are some good resources for other regions and the general types of insects are the same. Just keep in mind that many of the species mentioned will not be found in Michigan. Here is one example:
Field Guide to Insects and Diseases of Arizona and New Mexico Forests: https://nmdeptag.nmsu.edu/media/pdf/field-guide-insects-and-diseases-of-AZ-and-NM-forests.pdf
For closer to Michigan, you might find this article about insects in firewood from Purdue Extension, helpful: https://extension.entm.purdue.edu/publications/E-67/E-67.html
In a nutshell, larger tunnels (>1/8") that meander just under the bark, are usually from flat-headed borers (Buprestidae). Larger tunnels that penetrate into the sapwood/heartwood, are usually from round-headed borers (Cerambycidae). Smaller tunnels and galleries (<1/16") are from bark beetles or ambrosia beetles (Scolytinae). All of those previously listed are beetles (Coleoptera). There are some Lepidoptera (moths) and Diptera (flies) that also bore in the wood of conifers, so if you see something that doesn't seem to fit with beetle damage, then it may be something else that did the damage. The Christmas Tree Pest Manual from MSU Extension (https://www.canr.msu.edu/resources/christmas_tree_pest_manual_e2676) could help you determine if the damage was done by one of the moth pests of conifers in Michigan.
