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In the conventional treatment of insect epidemics it is usual to recognise a number of development stages which may be follows:
1. The biotic balance; this is the normal state, previous to the epidemic, in which a balance is maintained at approximately the normal level.
2. The preparatory stage; in which there is an increase in insect population but no visible damage.
3. The prodromal stage; in which damage is visible but not of economic importance; there is a definite increase in insect numbers.

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The approach in this paper is from the stand point of a systematic zoologist interested in verte brate groups. The illustrations are taken, and the ecological factors emerge, from a study of birds. Admitting that the rate and degree of change in the total environment of any organism may be negligible in relation to the short term of a single individual life history, no study of dis tribution nor hypotheses of speciation and phylogeny can disregard the factor of environ mental change. Some of the factors to be taken into account in varying degree are:

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The history of any botanical community is often as important in explaining its composition as are the environmental factors which form the normal study of ecology So the ecologist will need to consider problems of plant-distribution, just as the plant-geographer must take into account the ecological requirements of the species.

JOHN ANTHONY GIBB

July 1919–January 2004
M.A. Law, Oxon
D.Phil. (Oxon)

A generation of scientists, even of ecologists, has grown up for whom John Gibb is not a household name. This is not surprising as he retired in an official sense in 1981, though he continued to work and to publish until 2001. This essay presents a summary of John's achievements and his valuable contributions to ecology.

Information on toxic loading and piece-weight distribution are used to calculate an index of the number of baits which an animal must encounter and eat before the probability of death exceeds 99%. It is termed the 99% bait quality index (99BQI).The index shows that, on average, rabbits of median susceptibility to 1080 must find 4.2-5.4 unscreened carrot baits; possums of median susceptibility must find 6.5-8.4. Indices for 1080-tolerant rabbits and pos- sums ranged from 6.2-15.6 baits.

A survey of matai (Podocarpus spicatus) / totara (Podocarpus totara var. waihoensis) forest in South Westland recorded that c. 600 ha of these forests remain from a possible former 43,000 ha. Basal discs cut from logged or windthrown matai and totara showed a strong linear relationship between diameter and age (annual growth rings). Detailed surveys of stands showed grouping of size class distributions, reflecting the seral nature of these forests.

Clubiona cambridgei is a short-sighted hunting spider that lives on bushes of New Zealand flax (Phormium tenax) and constructs silken nests within tunnels formed by rolled- up leaves. Intraspecific interactions in this species are integrally related to the use of nests. In laboratory observations, mating was never observed outside nests, although virgin females readily mated while inside their nests. A distinctive courtship preceded copulation in every case, and displays occurred also in other types of interactions. Interactions were more lengthy at than away from nests.

In four populations of possums more than 94 % of animals accepted each of the three types of dye-marked, non-toxic bait. In a fifth trial, conducted in summer, only 68 % of the population accepted bait. This poor level of acceptance was attributed to the abundance of natural food available, as indicated by the good condition of the animals. In a trial with toxic bait approximately 25 % refused either to eat a lethal quantity of toxic bait or to eat any toxic bait at all, compared with 98 % acceptance in the non-toxic control trial.