5o8 INTERACTION OF ENDEMIC 



pasture plants, have all contributed to this wholesale destruction 

 and displacement of indigenous species. The disappearance of mos- 

 quitoes and sand-flies in settled districts where they were formerly 

 very common is a case in point; — ^where they disappeared, it is 

 tolerably certain other species not so well known became scarce at 

 the same time. Unfortunately accurate data are not obtainable, for 

 at the time that settlement began, very little was known of the insect 

 fauna as I have shown, and even now, as already stated, whole groups 

 are imperfectly known. 



The introduction of many insectivorous birds, including pheasants, 

 quail, starlings, minahs, species of Fringillidae, and others, must also 

 have accounted for the destruction of immense numbers of insects. 

 At one time the wide tussock-covered hills and plains of both islands 

 were just alive with grasshoppers, and in the summer months they 

 sprang up before the pedestrian literally in thousands. To-day they 

 are rare over wide areas where formerly they abounded. Fereday 

 wrote in 1872: 



In the early days of the Canterbury Settlement quails, larks and other 

 birds that fed upon insects and their larvse abounded on the plains, but 

 the quails have been exterminated, the larks have become comparatively 

 scarce, and the other birds have almost disappeared. So long as the 

 plains remained open and uncultivated, extensive grass fires, sweeping 

 over the land consumed an enormous amount of insect life, and took the 

 place of the counter-check which was being removed by the decrease 

 of the birds ; but within the last few years inclosures and cultivation have 

 been rapidly extending around Christchurch, and forming a nursery for 

 the preservation and increase of the insect race. A luxuriant and abundant 

 vegetation has sprung up for its food and shelter, and it is comparatively 

 freed from the ravages of fire and the attacks of its feathered foes. 



Lizards (especially Naultinus elegans, N. grayi and Lygosoma 

 moco) were also extremely common in the open country fifty years 

 ago, but are now comparatively rare. Burning the surface growth 

 is largely responsible for their destruction, but the abundance of wild 

 cats, which in some parts are encouraged as counteracting to some 

 extent the rabbit pest, is also accountable for many. 



The introduction of species of Salmonidae, of perch, carp, etc., 

 into the lakes and rivers of most parts of the country has produced 

 equally important changes. Some species of fish have been exter- 

 minated wherever the introduced forms have established themselves, 

 e.g. native grayling {Prototroctes oxyrhynchus), kokopuru, minnow, 

 etc. (species of Galaxias), and smelt {Retropinna richardsom). Similarly 

 the native species of crayfish {Paranephrops planifrons, P. zealandicus 

 and P. setosus), shrimp (Xiphocaris curvirostris), and species of fresh- 

 water Amphipoda, have been eaten out in streams stocked with trout. 



