Roundhead Borers

Leonard and I continue to monitor a site burned by the Cove Fire in July and August of 2017 (see 08-28-17 “Resilience”). The fire burned approximately 30,887 acres in the Modoc National Forest near Adin CA (Modoc County).

When standing amid heavily burned and charred ponderosa pines, we can hear a surprisingly loud chewing sound. By peeling away the charred bark the source of the chewing is revealed – roundhead borer larvae of longhorn beetles that belong to the Family. Not being an entomologist, I will not attempt to identify the larvae to species.

There are over 25,000 species of longhorn beetles worldwide. The beetles are characterized by long antennae, often as long as or longer than the beetle’s body. The larvae of longhorn beetles bore into wood.

The life cycle of a longhorn beetle begins when an adult beetle mates and lays its eggs in or on wood. Depending on the species, longhorn beetles lay their eggs in living or dead wood and even wood in buildings and furniture. After (again depending on the species for all the time ranges mentioned) 1 to 4 weeks the eggs hatch and the larvae feed within the wood for 1 1/2 to 12 years before pupating. Roundhead borers leave mostly unbranched tracks (the tunnels constructed when the strong roundhead borer jaws feed on the starch and other compounds in the wood) and their frass (more or less solid excreta and other debris) is coarsely textured. It takes the pupa 1 to 4 weeks to change from a larvae to an adult. Pupation occurs near the wood surface. Adult longhorn beetles fly for 1 to 35 days and feed on sap, pollen and nectar. During flight the beetles mate, lay eggs and the cycle begins again.

The Cerambycidae Family was named for the shepherd Cerambus. According to Greek mythology, Cerambus was turned into a large beetle with horns after an argument with a nymph.

These roundhead borer larvae are chewing the ponderosa pines along Modoc National Forest Road 40N11 near Adin CA (Modoc County).

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5 Responses to Roundhead Borers

  1. usermattw says:

    How strange it must be to stand in a seemingly dead forest and hear chewing.


  2. tonytomeo says:

    That is a disconcerting sound coming from dead pines. They get into the dead ponderosa pines here. Fortunately, we do not lose too many of them.


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