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THE LIFE HISTORY OF THE AMBROSIA BEETLE XYLOTERINUS POLITUS (COLEOPTERA: SCOLYTIDAE)1
Published online by Cambridge University Press: 31 May 2012
Abstract
Head capsule measurements of the ambrosia beetle Xyloterinus politus (Say) revealed three larval instars. The xylomycetophagous larvae lengthened their cradles and a positive correlation existed between head width and cradle length. A sex factor of 0.84 was in favor of the female adults. Dissection of active galleries revealed only a single female per gallery. Males were never seen to initiate or excavate a gallery and were forced from the entrance hole by the female when placed in an active attack. The gallery system studied was simple, the entrance hole penetrated into the sapwood for a variable distance before it branched into secondary tunnels at right angles to the main gallery.
Eggs were laid singly in cup-shaped cradles excavated by the female. The cradle openings were plugged with frass throughout the duration of the immature stages. Callow adults emerged from the cradles by forcing the frass plug covering the entrance, and re-entered, their position reversed to feed upon the ambrosial fungus growing on the cradle walk X. politus overwintered as an adult in the old cradles and galleries. Larvae of Ipideurytoma sp. (Hymenoptera: Eurytomidae), probably a larval parasite of X. politus, were found in cradles.
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- Copyright © Entomological Society of Canada 1967
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