A NUTRITIONAL STUDY OF INSECTS 53 



for the purpose of extracting all the nutriment possible from the 

 food already comminuted. This would lead us to the case of the 

 Cecidomyiid, Asphondylia prunorum, which was studied by 

 Neger ('08 a, b; '10). The adult deposits with the egg on the 

 prune tree a mass of fungous spores and mycelia which serve as 

 food for the larva and finally grow on the tissue of the gall formed. 

 The fungus itself is not concerned in the gall formation, but 

 merely serves as food for the gall inhabitant. Upon the emergence 

 of the adult insect the fungus breaks through the gall and can be 

 seen as a white growth from the outside. The fungus, a Macro- 

 phoma species, is very similar to the fungus fed upon by the wood- 

 boring beetles (Xyleboi-us, Xyloterus, etc.) and has never been 

 found elsewhere; the galls have therefore been called 'ambrosia- 

 gallen.' 



At the pinnacle of this development may be placed the ambro- 

 sia beetles and termites. Schmiedberger ('36) first gave the 

 name 'ambrosia' to a protein-containing white substance which 

 he found to be the food of the insect rather than the chips of 

 wood cut by them. This was made certain by the observations 

 of Hartig ('44) and it was also decided that the white substance 

 was a fungus which grew on the wood cuttings. The subject 

 was further studied by Hubbard ('97) in America and Neger ('07) 

 in Germany. Though these two investigators do not agree in 

 all their observations, they have made certain that different spe- 

 cies of fungi are associated with different species of beetles and 

 that these associations are constant for the same species in spite 

 of changes of host plants or parts of plants eaten (Xylebonis 

 saxisenii). The fungus is independent of the food plant, but de- 

 pendent on the products of the insect. Hubbard maintains that 

 the female consciously carries the spores of the fungus to the new 

 gallery and sows them. Neger, however, beheves that the spores 

 become attached to the highly sculptured wing cases of the female 

 as it leaves the larval gallery, the walls of which are coated with 

 the fungus. The fungus that grows on the walls of the galleries 

 is different for different beetles, but in general is composed of 

 either a chain of round cells which are assembled in an irregular 

 heap or of upright threads with a round corpuscular cell on the 



