A serious spruce budworm outbreak has been affecting Quebec since 1968. In regards to the considerable investment required in aerial spraying, it is important that a general spraying policy be defined for the Quebec government. This task was entrusted to a study committee on the economic feasibility of aerial sprayings. The present report deals with the first part of the committee's task and examines western Quebec only; it sums up the work of four people during six months. The main element on the general spraying policy is the rule of decision that reads:

"The maximum outlays economically justifiable for aerial spraying against spruce budworm must be less than the value of loss prevented by the treatment".

The value of loss prevented is a potential value and is not limited to woody matter and to the present users. The approach followed in this study is the marginal approach applied to nine spraying alternatives. In the absence of any similar economic study, it has been necessary to develop a suitable economic model. Spraying cost is compared to value saved. Bio-physical data are integrated with economics, as the final decision is an economic one.

Due to the lack of time, only woody matter was considered. Several hypotheses are determined in order to define the analytical frame of reference for the study.

Legislation and controls over forest protection against insects in Quebec and abroad, were analyzed. Chapter V shows how spraying policies must be integrated with other government policies.

Efficiency  of the control methods is a prerequisite to economic calculation. The nine spraying alternatives are defined in regard to choice of stands and interval between two consecutive spraying.

Alternatives are compared in terms of three economic criteria and direct, indirect and total values are taken into account. The regional impact of the outbreak is analyzed in terms of employment, salaries, and timber supply for the mills. Forest product demand is analyzed only briefly due to lack of time.

The committee recommends that the government of Quebec chooses Option 7 for the area studied here. This option is defined as the spraying, for two consecutive years followed by two more years without spraying, of all conifer and mixedwood stands, beginning with the second year of severe defoliation.