In order to investigate the possible means of controlling introduced plant pests, the course that has been considered advisable to follow has been that of a general biological survey of the particular species under its native conditions and, so far as is possible, a comparison between this and a similar survey in the country to which it has become introduced. Such a survey should include the following aspects :—

Germination of seed : Normal percentage germination, germination of fresh and old seed, dormancy, “ hard ” seed, effect of varying external conditions or previous treatment upon germination of hard seed (if present). Seed reserves in soil ; continuous or discontinuous germination.

Establishment of seedlings : Effect of grass, leaf debris, bare soil, etc. ; root development ; causes of mortality.

Flowering : Periods of flowering, number of flowers ; mode of pollination.

Seeds and dispersal : Number of seeds, manner of dispersal, mortality before germination.

Relation to plant communities.

Relation to climate and soil types.

Geographical distribution.

Relation to insects : Insects found on the plant at different seasons ; nature and extent of damage to vegetative parts, flowers and fruits.