Abstract
A mathematical treatment is proposed, utilising the methods and notation of matrix algebra, for evaluating the theroetical effects on the growth and structure of a population of the removal of individuals in particular age groups or stages in the life history. Formulae are derived to establish what proportions of given age groups or stages, individually or in combination, can be withdraw from the population whilst permitting its maintenance at a constant level. It is pointed out that these methods, appropriate to the situtation in which the population is exploited by a cropping procedure, can be extened to the special case of population control, in which it is desired to minimise or eliminate the population. The methods are illustated by numerical examples based on census observations on a growing population of Lasioderma serricorne (F.).