December. '21 J holloway: corn borer vs cane borer 483 



Progress of Infestation 



In a discussion at the meeting of the Association of Economic Ento- 

 mologists at St. Louis on December 31st, 1920, it was mentioned that 

 the infestation by the European corn borer was extremely low in places. 



Judging from the related insect, however, the opinion of the writer 

 is that this means very little. If the infestation is very low now it may 

 be some years before there is an important loss, but the loss is probably 

 to be expected. 



Some years ago the writer happened to make examinations on a plan- 

 tation which had previously been under water for a ntmiber of weeks, 

 all that section of the country having been overflowed. The infestation 

 of sugar cane in the fall was 4% of the stalks, which would mean that 

 at the time the com was gathered there w^as practically not a trace of 

 borers in the fields. The writer made a point of visiting this plantation 

 the following year, and he found that the infestation of sugar cane had 

 risen to 6%. One year later it had climbed to 68%, and the following 

 year it was 87%. With an 87% infestation in sugar cane, late corn 

 would not have been successful. 



The writer cannot predict similar activities on the part of the European 

 corn borer, but it evidently develops earlier in the season than the sugar 

 cane moth borer, and even m.ore damage might reasonably be expected 

 of it. It should be pointed out that the sugar cane species is really a 

 tropical insect which was brought to Louisiana in shipments of seed cane, 

 and that it develops much more slowly than do insects which are native 

 to Louisiana. The European com borer, on the other hand, comes 

 from a region where the climate more resembles that of the northern 

 states, and it apparently reaches a heavy infestation m.uch earlier in 

 the year. 



Habits of Adults 



Caffrey (1) states: "Soon after emergence the moths mate and begin 

 to deposit eggs. They remain quiet during the day, hiding in patches 

 of grassland or underneath the leaves of jilants. At night they fly 

 from plant to plant, depositing their eggs in flat, irregular-shaped masses 

 of from 5 to 50 eggs each, on the underside of the leaf. Each egg over- 

 laps the adjoining eggs in the manner of shingles." 



This was w^ritten about the European corn borer, but it almost perfect- 

 ly describes the habits of the sugar cane moth borer. J 



