tiiLGENuoRF. — Insect-life at Cans Mountain Biological Station. 137 



would soon lead to its extermination if there were a hungry insectivorous- 

 bird population. The highly protectively coloured Scoparia philerga of 

 the forest-glades is quite invisible as it sits at rest on the trunks of the 

 beech-trees, but if one walks noisily forward the moth will fill the air in its 

 fluttering hundreds. It is true that in both these cases the kind of noise 

 demanded is not that associated with a bird-attack, and the short zigzasf 

 flight and quick settling may lead to escape from other dangers. Still, 

 protective coloration and the crouching habit are nearly always associated, 

 and in many insects at Cass that association does not exist. (2) The 

 second fact indicating a more plentiful bird-life in the past is the great 

 profusion of berries and drupes borne by the shrubs. The close connection 

 between the presence of birds and the production of succulent fruits is 

 denied by Guppy,* bat his views do not appear to have received wide 

 acceptance. The writer's view is that if there were no frugiverous animals, 

 then the characteristic of producing brightly coloured, fleshy, and palatable 

 fruits would not have been fixed in so high a degree as is commonly found, 

 and that a large number of plants bearing such fruits is evidence of a large 

 bird population. The suggestion that frugiverous birds would have no 

 effect on the insect-life is of little weight, as the annual variation in the food 

 of birds is not well known. The variation is probably considerable, as is 

 indicated by the fact that so purely a grain-eating bird as the sparrow feeds 

 its nestlings for about six weeks on nothing but insects. Of more import- 

 ance is the suggestion that the birds probably visited certain districts only 

 during the fruiting season of the plants they specially favoured, and at that 

 time would almost entirely neglect insects as food. 



Except the birds, the only native land vertebrate is the common lizard 

 {Lygosoma moco), which is found not infrequently on the tussock. In the 

 lakes and streams, however, fish, especially trout, are very common, and 

 the introduction of trout must have made an enormous difference to the 

 insect and probably to the bird population of the district. Hudsonf has 

 shown that the stomachs of 60 trout taken from various localities contained 

 4,804 Neuroptera, 662 other insects, and 28 other animals. At this rate 

 the reduction of Neuroptera in our streams must be enormous, and, as these 

 insects, while aquatic in their immature stages, are aerial when adult, 

 insect-eating birds may also have suffered a reduction in food-supplies 

 sufficient either to drive them from the neighbourhood or at least to compel 

 them to take to other food. In either case the reaction upon the general 

 insect-life of the district must have been very considerable, and it becomes 

 obvious that the insects are, on the whole, living in an environment that 

 is much changed since the advent of the white man. 



Two important factors in the environment are dead sheep and white 

 flowers, for these are correlated with the two most striking features of the 

 insect-life — namely, blow-flies by day and moths by night. The two com- 

 mon blow-flies are Calliphora quadrimaculata, the well-known bluebottle, 

 and C. oceana, which is somewhat smaller, and is covered with bright- 

 yellow hairs below. Both these species occur in hundreds everywhere, 

 and fill the air with their buzzing wherever a human being rests for a few 

 minutes. When a sheen dies the blow-flies are attracted from near and 

 far : each lays a hundred or more eggs upon it, and the resultant maggots 

 are fully fed through their active life. But the thousands of flies thus 



* H. B. Guppy, Observations of a Naturalist in the Pacific, vol. 2, p. 99, 1906. 

 t O. V. Hudson, New Zealand Neuroptera, West and Newman, London, 1904. 



