296 Insect and other Invertebrate Fauna 



The average number of insects per sample was 31-95. 



The following orders were represented in the percentages given 

 Collembola 28-14; Thysanura 1-78; Orthoptera 0-55; Thysanoptera 0-96 

 Hemiptera 0-27; Lepidoptera 1-91; Coleoptera 15-30; Diptera 22-13 

 Hymenoptera 28-96. 



The dominant order in number of species present was the Coleoptera, 

 with 14 species. The number of species in the different orders is shown in 

 Fig. 6. 



The most abundant species of insects were Myrmica laevinodis, which 

 made up 27-9 per cent, of the total insects, Onychiurus ambulans 6-8 per 

 cent., and Onychiurus fimetarius 6-5 per cent. 



Seven species of Myriapoda (excluding Symphyla) occurred in this 

 plot, and thirteen species of Arachnida. 



10. Comparison of the Faunas of the Two Plots, 



It is noticeable that in both the plots the Oligochaeta (Limicolae), 

 Formicidae and Collembola were much the most abundantly represented 

 groups, and that the Diplopoda, Oligochaeta (Terricolae) and Acarina were 

 also very numerous in both plots. There was not very much difference 

 between the numbers of Elateridae larvae in the two plots, the numbers 

 being 198,653 per acre in plot 2, and 164,983 per acre in plot 3. It is also 

 noticeable that the numbers of Tipulidae larvae and Hepialidae larvae 

 are the same for both plots. 



Other groups showed considerable difference in numbers between the 

 two plots. Diplopoda occurred at the rate of 1,367,002 per acre in plot 2 

 and 595,959 per acre in plot 3, while Trichocera larvae occurred at the rate 

 of 367,002 per acre in plot 2, but only at the rate of 23,567 per acre in 

 plot 3, and Chironomidae larvae, which were found at the rate of 515,151 

 per acre in plot 2, were only found at the rate of 26,936 per acre in plot 3. 



Most of the other groups occurred in somewhat greater numbers in 

 plot 2: only one or two groups were found to be more plentiful in plot 3. 

 Amongst the latter were the Cecidomyidae (larvae), 212,121 per acre in 

 plot 3 and 195,286 per acre in plot 2, and the Chilopoda, 215,488 per 

 acre in plot 3 and 208,754 per acre in plot 2, although the differences in 

 these cases are not large enough to be of importance. 



The equal or almost equal numbers of Elateridae, Tipulidae and 

 Hepialidae larvae appears to show quite clearly that the continued use 

 of farmyard manure does not cause an appreciable increase in the 

 numbers of these injurious species although this manure appears to 

 introduce or attract the injurious Diplopoda and certain non-injurious 



