The larvae of three species of Phryganeidae were placed in so-called 

 "courtyards"* in which they were offered various vegetable foods; the 

 larvae of Phryganea striata rejected some of these foods but showed 

 a distinct preference for detritus of fallen leaves; they readily fed on 

 filaments of Cladophora; the same food and also pine needles were 

 preferred by the larvae of Oligostomis reticulata and Neuronia 

 ruficrus. When the larvae of the same species were starved and then 

 offered any kind of food, e. g., tree leaves, their daily food index** varied 

 from 58.2— 80.7%, i. e., it was high; when they were fed with Cladophora, 

 the index was higher: 74.8—88.0%; when deprived of vegetable food, the 

 larvae also took animal food, but showed a low daily food index; feeding on 

 oligochaetes: 6.3 — 16.8%; on Chironomidae: 2.8 — 10.0%; on Daphnia: 

 4.9 — 11.8%; if both vegetable and animal food was available, the larvae of 

 Phryganeidae rejected animals and always fed only on plants; the larvae 

 of Phryganeidae thus change to animal food only if forced by starvation; 

 animal remains repeatedly found in the stomach of the larvae of Phryga- 

 neidae are mainly small animals accidentally swallowed together with 

 vegetable food. 



The larvae of Leptoceridae are for the most part phytophagous. They 

 consume large quantities of vegetable food, e. g., the daily food index of 

 young larvae of Mystacides longicornis and Leptocerus 

 senilis is 102.7 — 107.8% when fed with C 1 a do ph o r a; these larvae 

 reject animal food (oligochaetes, Tendipedidae, Daphnia) even when 

 starving. 



The larvae of L. senilis and L. fulvus are often found in lakes 

 among plants on stones; in oligotrophic lakes, these plants are mainly 

 diatoms; the larvae of L.fulvus penetrate deeply into these thick, slimy 

 61 incrustations and are often completely buried in them. Both species live 

 well on vegetable food and do not feed on small animals even when starved; 

 however, it is interesting that in some places they feed on larger animals 

 in plants growing on stones, e. g., on sponges; they eat galleries into the 

 sponges; it is possible that these species consist of two different physio- 

 logical races with a different type of feeding; the stomach of larvae taken 

 from sponges are filled with spicules of sponges (Siltala, 1907:16). 



The larvae ofOecetis furva are typical inhabitats of overgrowths 

 on stones; their cases consist of plant particles and they feed on very 

 diverse vegetable food; in experiments in the "courtyards" the larvae 

 showed an equal preference for decomposing tree leaves, threads of 

 Cladophora and Vaucheria and coarser vegetable food, e. g., sedge 

 leaves. When starved, these larvae eat small numbers of Daphnia 

 (food index 2.4%); animal remains are frequently found in the stomach of 

 Oecetis furva larvae caught in nature (frequency 41 .6%). 



When the bottom inhabiting species of Oecetis (Oe. ochracea, 

 Oe. lacustris) (which build cases of sand) are fed with vegetable and 

 animal food, they accept both readily; they are thus typical representatives 

 of the group of larvae of Leptoceridae with mixed feeding, although their 

 dagger- shaped mandibles seem better adapted for feeding on animals. 



* "Courtyards" are a device for the study of the selective ability of invertebrates for various kinds of food, 

 suggested by N.S. Gaevskaya (1939:1064—1066). It is a round aquarium divided into sectors ("courtyards") 

 by small partitions which do not reach the middle of the aquarium. Different foods are placed in each 

 "courtyard"; the animals are placed in the center of the aquarium; they crawl freely from one courtyard 

 to another, and concentrate in greatest numbers in the courtyard containing the preferred food. 

 "* Food index is the ratio of the weight of consumed food to the weight of the body of the larva (in %). 



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