Oviposition Behaviour of the Jack-pine Sawfly, Neodiprion americanus banksianae Roh., as Indicated by an Analysis of Egg Clusters

Abstract

This study was undertaken as part of a broader investigation of the behaviour of the jack-pine sawfly, Neodiprion americanus banksianae Roh. The greater part of the investigation was directed towards an understanding of larval group-feeding behaviour, but in order to clarify the situation in which this insect begins larval life, large numbers of egg clusters were analysed with special attention paid to the positional relations of egg-bearing needles. Such analysis has permitted certain inferences on the oviposition behaviour of this insect and this indirect information is of value in view of the difficulties experienced in efforts to induce this species to oviposit under laboratory conditions for direct observation. Fortunately, egg clusters obtained from the field are well adapted to descriptive measurement and analysis, for in order to lay its full complement of eggs the adult female sawfly must select as many as 20 to 30 needles, thus leaving behind it a readily measured record of its egg-laying behaviour.