Mendel, Z., Dept. of Entomology, ARO, Ilanot, Israel

Observations on the seasonal development of Phoracantha semipunctata (Fab.) (Coleopteia: Cerambycidae), the eucalypt borer, were carried out in 11 plantations of Eucalyptus camaldulensis Dehn. and two of E. gomphocephala DC, situated in areas from Qiryat Shemona (Upper Galilee) to Ze'elim (western Negev), using trap logs. Egg masses of the borer were usually found during the warm season but also in small numbers during the winter. Larvae which hatched during the colder season generally died, due to the relatively accelerated drying of the bark. Mean minimum duration of development from egg laying to the onset of adult emergence was ca 100 days for individuals which began to develop between spring and mid-summer (March to July);ca 215 days for the late summer brood (August to September); and ca 195 days for the autumn brood (October to November). Mean larval development comprised about 66%, 64%, 36% and 81% of the total development period in spring, early and mid-summer, late summer, and autumn, respectively. Mean spring development of the larvae lasted 70 days in fresh material vs 118 days in old (partly dry) material. The pupation period lasted between 32 and 40 days when it began between spring and late summer, and ca 110 days when it started in the autumn. When adult emergence began between spring and mid-summer it was usually completed within 2-3 months, whereas when starting from late summer onward it lasted up to 9 months. Emergence was arrested during the winter and resumed with a rise of temperature in the spring. The borer develops two or three annual generations, depending upon the area. © 1985 Springer Science + Business Media B.V.