I’ve received a few calls about sugarcane beetles damaging corn.  I will refer you to a previous article posted on April 5th (link below).  There were images of the beetles and their injury in this article.
http://www.utcrops.com/news/2011/04/managing-for-sugarcane-beetles-in-corn/

The above article went in to detail about the damage they cause and some at-planting treatment considerations.  We’ve been running black light traps and catching the adults in pretty fair numbers over the last few days.  I mention this to make the point that adults are mobile night fliers and can infest fields pretty quickly.  It is very important to scout your fields for signs of injury (dying, wilted plants).  The beetles can be found below the soil surface near damaged or adjacent plants.  They often move down the row, so there may be several consecutive damaged plants.  They can injure plants up to 2 ft tall, but smaller plants are even more susceptible.  As mentioned in the previous article, fields where Cruiser was used (e.g., Pioneer hybrids) will be at greater risk than those where Poncho was the seed treatment (e.g., DeKalb hybrids).  But neither Poncho 250 nor Cruiser provide complete protection.

Foliar insecticides sometimes provide partial control, but there are no guarantees.  Regardless, I would recommend treating anytime the beetles threaten to reduce stands below an acceptable level.  Note that damaged plants may not die but often will not produce a harvestable ear.  Very few products are specifically labeled for sugarcane beetle.  The most common insecticides used are bifenthrin (Brigade 2E, Discipline 2E, Fanfare 2E) at 5-6 oz/acre or Lorsban 4E at 1-2 pints per acre.