216 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



Extent of Injury. — During the past summer and fall 75 to 80 per 

 cent of field corn grown in bottom land which had been in corn last 

 year and winter plowed was attacked by this pest. The extent of this 

 injury to each ear varies but the total loss is at least 10 per cent of the 

 crop. In case of fall grown sweet corn 100 per cent of the ears were 

 attacked with practically a complete loss of the crop. With such 

 damage as this the total loss throughout the corn belt amounts to 

 several millions of dollars. 



The actual damage does not stop with the corn which is consumed 

 but fungus growths of the smut type follow up the work of the worm 

 and destroy m.uch more of the corn. Some of these smuts seem to have 

 poisonous properties and some veterinarians attribute the poisoning 

 of stock fed on wormy corn to these smuts. If this is true the pest is 

 indirectly responsible for such losses. In the past three years a great 

 many animals have been lost due to poisoning in this state. 



Experiment for Preventing Injury. — Since it is not possible to 

 reach the pest successfully with remedies generally recommended and 

 since cooperation of farmers is not possible, an attempt has been made 

 to find some treatment of corn which will protect the crop during the 

 growing season. The pest being one which feeds first on the silk and 

 later enters the ears, it was thought that some treatment of the ears 

 at /^shooting" time might accomplish this. 



We have used a number of materials both in the form of a spray 

 and as a dust. It is necessary that the material used must not injure 

 the silks or ears and if it is to give results it must either poison the 

 young worms or repel the moth or worms. The repellents used have 

 given no results so far. The poisons in some cases injured the corn, 

 in other cases gave no results, while in case of powdered arsenate of 

 lead the damage was reduced from 75 to 35 per cent. 



This work is to be continued along those lines which have proven 

 most successful. This year we used 5 acres of field corn and one- 

 fourth acre of sweet corn in our experiments. While at present the 

 results seem rather discouraging I believe an economical treatm.ent 

 can be found that will save the corn crop. 



Mr. Wilmon Newell: I would hke to ask Mr. McColloch 

 whether he made any observations on the feeding of the larvae on the 

 silks before they made their way inside the shuck. 



Mr. J. W. McColloch: They may feed for a few hours after 

 hatching. They feed on the egg shell first and then start down into 

 the ear. We have not carried on very much work along that line but 

 they move pretty rapidly to the ear and probably v/ithin six hours 

 after they hatch they are down in the tip of the ear. 



