Subject: Bugs on Quercus ilex (Spain)
Location: Salamanca (Spain)
February 20, 2017 6:14 am
I enclose three pictures of two bugs (larva and adult) found on young Quercus ilex (inside). The larva is about 25 mm and de adults about 2 mm. They were found in Salamanca (central western Spain).
They don’t look like the usual borers in the area.
Thank you very much
Signature: Luis Carlos Jovellar (Salamanca, Spain)
The images of the larva you submitted appear to be Round-Headed Borers, a general name for the larvae of members of the Longhorned Borer Family Cerambycidae. See this BugGuide image for comparison. They are unrelated to the adult insects you submitted which we will address at a later date. Knowing the host plant is often a tremendous assistance in the identification of larval stages. According to the opening sentence of a scholarly article we located on Springer Link: “Cerambyx welensii Küster is one of the greatest threats to Quercus suber L. and Quercus ilex L. in Spain.” While that is not a definitive identification for the Round-Headed Borer you sighted, chances are good that it might be a correct identification. iNaturalist has an image of the adult. Your larva has a distinctive yellow coloration. The Espiritu de Arbol blog has images of adults and larvae.