WATER BEETLES IN RELATION TO PONDFISH CULTURE. 
255 
Ephemerida, and the Odonata and Coleoptera were tied for third place. Pearse 
divided the fish foods into nine classes, the first four of which in the order of their 
importance were: (1) Insect larvae, oligochaetes, and leeches. (2) Entomostraca. 
(3) Fishes and frogs. (4) Insect pupae and adults. In the present instance the 
larvae and adults are combined in one table, while the pupae, transforming out of 
water, are never eaten by fish. This beetle food, therefore, belongs partly to the 
class considered of greatest importance and partly to the class placed fourth in 
the list. 
Pearse’s table may well supplement the preceding one, since it includes several 
kinds of fish not mentioned by Forbes and also adds new items to the diet of other 
species. Of greatest interest is the inclusion of the German carp, of which 40 
young specimens, varying from 15 to 64 mm., were examined. These had eaten 
freely of gyrinid larvae, haliplid adults and larvae, dytiscid adults and larvae, and 
hydrophilid larvae, the sum total forming an amount of food surpassed only by the 
Dip ter a and Entomostraca. Pearse said (1918, p. 258) : 
The German carp during its first few weeks after hatching from the egg feeds largely on entomostra- 
cans and rotifers; after that it turns more to insect larvae. 
And of this insect food the beetles are second in importance. 
It is also worthy of note that three young suckers, averaging 2 inches in 
length, had consumed enough dytiscid adults to form a respectable percentage of 
their total food. The little Iowa darter subsists almost entirely upon amphipods 
and insect larvae, and among the latter the beetles are second only to the Diptera. 
The only family of aquatic beetles not found in the food of the bluegill as 
given by Forbes was the Haliplidae. Adi of the 25 specimens of bluegill examined 
by Pearse contained haliplid larvae, the larger fish containing the greater amount. 
The large-mouthed black bass, the yellow perch, the black crappie, the golden 
shiner, and the mud minnow did not appear in Forbes’s list. 
Food of trout, by Chancey Juday. 
Kind of trout. 
Locality. 
Number 
examined. 
Length 
in centi- 
meters. 
Number 
eating 
Cole- 
optera. 
Average 
percent- 
age of 
Coleop- 
terous 
food. 1 
Salmo sebago 
Twin Lakes 
19 
20-70 
4 
73 
Salmo stomias . . 
do 
64 
10-20 
25 
42.7 
Salmo irideus shasta 
106 
15-45 
37 
22.2 
Salvelinus fontinalis . . 
do 
29 
2.5-5 
1 
5 
do 
126 
10-33 
43 
15.7 
Salmo whitei 
Kaweah River 
12 
14-20 1 
30 
Soda Creek 
11-18 ! 
2 
12.5 
Salmo roosevelti 
Little Kern River 
V olcano Creek 
41 
18 
12-20 i 
12-28 
38 
12 
15 
2 
1 The total food is considered 100 per cent. 
It should be noted first of all that Doctor Juday (1907) made no distinction 
between aquatic and terrestrial beetles, nor between adult and larval forms. In all 
probability terrestrial species formed a large proportion of the total amount. This 
is especially true of the trout captured in running water. To judge from the long 
