338 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 15 



and soluble in both alcohol and water, as well as ether. Although the 

 attempt to obtain volatile oil was unsuccessful, there is some volatile 

 substance, since the drug has a distinct odor. Hillan, by treating it 

 with an alkali E-nd then distiUing, obtained a very small amount of a 

 substance which was basic and afforded alkaloidal reactions." 



Schweitzer^ gives the following analysis of fresh and dry com silk 

 (Table V) , and points out that the fresh and dry silks differ in the loss of 

 phosphoric acid by the former and increase of potash in the latter. 



Table V. — Analysis of Fresh and Dry Corn Silks by Schweitzer 



" Fresh silk Dry^Silk 



Grammes of dry matter 35.50 7.70 



Grammes of fine ash 1.21 0.23 



Percent of fine ash 3.39 3.00 



Silica 8.23% 7.93% 



Ferric oxide 1.05% 0.31% 



Phosphoric pentoxide 19.11% 14.25% 



Lime 4.32% 8.25% 



Magnesia 7.71% 6.98% 



Potassa 42.27% 49.66% 



Soda 1.06% 2.66% 



Total 83.75% 90.04% 



Missing 16.25% 9.96% 



None of these writers gives a definite clue to the source of the odor 

 in the silk unless it be the reference of Hare et al in which they attribute 

 it to a volatile oil. Thus far the writer has been unable to find anything 

 in chemical literature treating of the crystalline principle, maizenic acid, 

 other than that it is a compound present in the styles and stigmas of 

 Zea mays. 



While the odor of com silk apparently plays an important part in the 

 attraction of the earworm moths to the com plant, the writer is aware 

 that other factors must be considered. It has been mentioned that 

 when the silks are not present, eggs are deposited on the upper surface 

 of the leaves and on the stalks, and certain preliminary experiments 

 conducted in 1921 indicate that these also produce an odor attractive to 

 the moths. In addition, various morphological characters must be taken 

 into consideration. It has been observed repeatedly in the experimen- 

 tal plots that plants with smooth leaves and stalks have very few eggs 

 deposited on these parts in comparison with plants having rough hairy 

 surfaces. It is also worthy of note that throughout the wide range of 

 plants on which the earworm oviposits, there is an apparent selection 

 of rough, hairy surfaces. Collins and Kempton^ consider the prolonga- 

 tion of the husk beyond the ear, the thickness and texture of the husk 



^Schweitzer, P., Study of the Life History of Corn at its Different Periods of 

 Growths. Mo. Agri, Exp. Sta. Bui. 9, pp. 3-78, 1889. 



^Collins, G. H., and Kempton, J. H., Breeding Sweet Corn Resistent to the Corn 

 Earworm. In Journ. Agri. Research, 11:549-572, 1917. 



