A NUTRITIONAL STUDY OF INSECTS 61 



is the microorganisms themselves, and to a less extent the sub- 

 stratum. This assumption can safely be made on the basis of 

 the preceding experiments and the general lack of nutritive value 

 (for insects) of many of the substrata concerned. This interpre- 

 tation of the food of scavengers, etc., has never been given before 

 to the author's knowledge except in the case of Drosophila, as 

 mentioned above (Guyenot, Loeb, Schulze, Henneberg). The 

 data in the table are mainly derived from Malloch ('17) and 

 Williston ('08) . From a glance at the table it is apparent that a 

 large majority of the Diptera live upon microorganisms. There- 

 fore it might be well to include under the term Mycetophages all 

 insects which have hitherto been termed scavengers, coprophages, 

 etc. 



Parrott, Fulton, and Gloyer ('14, '15, '16) found that tree 

 crickets eat fungous ''myceha and spores which are unaffected 

 by the intestinal juices.''^^ This assumption is based on the fact 

 that the spores of fungi are not digested by Oecanthus, as ger- 

 mination takes place from pellets of material passed through the 

 digestive tract, and they believe 



it is possible that the spores may act as roughage and were eaten for 

 that purpose; but it appears more plausible that the spores still retain 

 on their surface some of the protoplasm of the ascus or pycnidium which 

 makes them palatable ('16, p. 12). 



The assumption that fungi are not digested, based as it is on 

 the evidence that many living spores pass through the digestive 

 tract, is not entirely justified in my opinion, since the same can be 

 said of yeast cells in the Drosophila larvae, although in this case 

 the plant undoubtedly serves as food. 



The leaf-cutting ant is a good example of a mycetophagous 

 insect. The fungus-growing habits of these Attiine ants should 

 really be depicted at the same time as the habits of termites, as 



2» The wound made in tree twigs in which the eggs are placed is plugged with 

 excrement and often becomes the seat of the development of cankers. Gloyer 

 and Fulton ('16) give a concise account of the literature on the dissemination of 

 plant diseases by insects. This is in large part due to the habit of insects of 

 feedjng on all available fungus and bacterial growths and in doing so getting the 

 body covered with spores which readily remain attached to the hairs and sj)ines 

 on the surface of the body. 



