The life history and morphology of the green spruce looper, Semiothisa Granitata GN (Lepidoptera, Geometridae).

Forest entomological control is primarily dependent on a thorough knowledge of the interrelationships of all insects existing in the forest. Some of these insects rise and fall in population and periodically are capable of causing much damage when a high population is attained. To these we devote our greatest attention. (Quite often, however, we mistakenly pass over other forest insects which appear to remain at a more or less constant level of population and which give us no economical concern. The biological importance of this latter group is axiomatically almost unknown. We know very little of the part played by such invertebrates in the forest insect community and of their probable importance as reservoirs of parasites and pathogens for other more destructive pests in infestation status. The green spruce looper, Semiothisa granitata Gn. is a forest insect which may be classed in the latter group. Throughout the forests of Canada and the United States it is exceedingly common. [...]This perplexing problem— why granitata had not increased in the past—was one of the reasons which instigated the writer to undertake a study of this insect as a subject of a thesis. [...