S. Mahunka szerk.: Folia Entomologica Hungarica 27/2. (Budapest, 1974)
regular Intervals may also be possible but this could only be proved by the thorough study of outbreaks during Several decades. During the short visit of the author to the Maprik Subdistrict in 1959, a large amount of material of Planococcus dioscoreae was collected (including a few alate males which must be very rare). The insects were sent for identification to Dr. D.J. WILLIAMS of the Commonvealth Institute of Entomology (London) who found that they represented a new species which he described a few months later (WILLIAMS, op. cit.) The author has no knowledge of further records of this mealybug species; it appears that it is most likely an endemic insect of the New Guinea mainland. Whilst studying insect and host plant relations at the Bishop Museum Fiels Station at Wau (now Wau Ecology Institute) in 1967, I found a very serious outbreak of what appeared to be a new pest of Dioscorea in a large village garden in the Wau Valley (altitudes approximately 1000 m.) The new pest was asawfly of the subfamily Blennocampinae (family Tenthredinidae) which the late Mr. ROBERT B. BENSON of the British Museum (Natural History), London identified Senoclidia purpurate ( SMITH) ( =furva KON.; viola- ceipennis CAMERON). He has kindly advised in a letter of the 31.V. 1967 that "this species has been recorded from Celebes, New Guinea, North Australia and New Britain, but its biology was previously unknown." Further he wrote that "another closely related species called Anisoarthra dioscoreae ROHWER was recorded in the original description as being foun on Dioscorea in South India and this, according to my records, is the only species previously recorded from this host plant." At time of the author' s visit to the vegetable garden in the Wau Valley most of the yam-vines were almost completely defoliated. However, both larvae and flying adults were still present in numbers. The larvae were, feeding gragariously and as some other sawflies do, they formed lines on the large yam-leaves and destroyed them by beginning to attack in the area of the apex and working their way backwards chewing through the whole leaf lamina including the midrib. Fully grown larvae were observed dropping to the ground for population. Many, relatively fast flying adults were seen and a couple of dozen specimens could be easily collected with a butterfly net during the author's visit to the vegetable garden. A number of specimens are in the collection of the British Museum (Natural History) and some others in the coRection of the Bishop Museum. This sawfly most likely has some natural enemies which under normal conditions keep its population density at a low level, but as suggested in the case of Planococcus dios coreae, it may occur in denser populations under unusual weather conditions. Undoubtedly, Senoclidia purpurata , as a native insect of Papua New Guinea, must have its native food plants in this country and its attack of cultivated yam is most likely exceptional. This is proved by the fast that no other records of its association with Dioscorea is known. As a pest of yam it represents a new ecomic record mentioned the first time in this paper. In 1968/1969 the large yam hawkmoth, Theretra ne s sus (DRURY), known as a pest also in other countries, appeared in higher than usual population densities in vegetable gardens of the Wau-Bulolo area of New Guinea causing considerable damage to yam foliage here and there. It is a widely distributed species which has been recorded -from four
