202 



Conservation Department 



Considering next, the months when the different kinds of insects 

 were most available, it is seen that the aphids, true bugs, beetles, 

 butterflies, moths, spiders and mites were taken in the greatest 

 numbers in June. In July the flies reached their highest numbers 

 as taken in the drift net catches, and in August mayflies, stoneflies, 

 caddisflies, ants, bees and wasps were most abundant. 



A study of all the stream drift organisms showed that 93.02% 

 were terrestrial in origin, i. e., adult animals non-gill-bearing 

 and non-aquatic. The remaining 6.98% was aquatic in origin, 

 i. e., nymphs, larvae or pupae of insects which are generally gill- 

 bearing and live in the water during their immature stages. This 

 shows that some aquatic insect larvae, which normally live attached 

 to the stream bed in a more or less fixed position, are constantly 

 being swept downstream by the current and when found thus, 

 they are probably consumed by trout. 



Pool Drift. — This was studied to determine the relative 

 amounts of drift food available in this type of stream condition. 

 The same apparatus was used in making these studies as was used 

 for collecting the stream drift. The stop net was always placed 

 at the point where the water flowed into the pool, to stop stream 

 drift from entering the pool. The drift net was placed at the lower 

 end of the pool where the water flowed out and thus the drift taken 

 was only that from the pool alone. 



Pools densely shaded by low brush (Table 6) produced the 

 largest amount of drift food, .13 grams per 100 square feet of 

 surface. The average production over all types of pool habitats 

 studied was as shown .0535 grams. 



Table 6. — Summary of Pool Drift 



No. OF 



DETERMINATIONS 



Type of stream 

 environment 



Average weight in 



grams of drift food 



from 100 sq. ft. 



of surface 



1 



Low brush densely shaded 



.13 



3 . 



Exposed 



.042 



1. . 



Semi-exposed 



.021 



2 



Arboreal 



.0205 









7 



Average over all types of environ- 

 ments 







.0535 









By comparing the average production in drift food per 100 

 square feet of surface over all types of habitats in streams and 

 pools (Tables 4 and 6), it is seen that pools are richer in drift 

 food per unit area by a difference of .0441 grams in favor of pools. 

 This being the case, then the more abundant drift organisms in 



