Observations on the biology ofCerambyx duxFaldermann in the Maltese Islands
AbstractThe distribution and host-range ofCerambyx duxFald. are summarised, and the detailed life-history in Malta, where the hosts are apple and pear, is described. Collections of various stages from host material indicate that the duration of the complete life-cycle is three years, including a 26–28 month larval period. The number of larval instars is estimated at six. Egg survival is dependent on high humidity. The early months of larval activity are confined to the superficial regions of the trunk and main branches of the host, penetration of the sapwood and heartwood occurring later. No special air-holes appear to be constructed by the larva. No exit gallery is constructed, and the emerging adult makes use of the existing burrows, finally gnawing its way to the exterior. The period of emergence is short (8–10 days) and may be stimulated by rain. Adult life lasts about one month. The average number of eggs laid per female is approximately 13. The main predator onC. duxlarvae is the larva ofZeuzera pyrina(L.). This is confined to the lesser limbs of trees in Malta, but extends throughout the trees in Gozo, and has practically eliminatedC. duxfrom this island.