The infestation may be categorized into three damage stages such as, mild, medium and severe. The palm with mild damage will have small holes and oozing of brown viscous liquid. In the second stage, the palm will show clear indication of damage, with extrusion of chewed up fibers and bad smell emanating from the wounded tissues. The frass mixed with sap forms small lumps and drops to the ground in some young palms. The severely damaged palm may show yellowing of leaf on the side of damage, besides all the above symptoms in a much more exagerated fashion. The damge to stem might be severe and can only be estimated upon proper inspection and cleaning of wounds. The palms in the first two categories of damage can be rescued to a large extent but the revival of the severely affected palms depends on several factors.
This is the most difficult part of the entire control program. If we know that a particular plant is having the pest we can use a control method. However, this is a hidden enemy and by the time it manifests externally, the internal damage is already done. So the emphasis should be to adopt methods to identify the palms with early symptoms of damage.
In recent years several electronic devices have been developed and tested. Some have given good results. But the question is, are these sophisticated electronic machines really help the average farmer or just tools in the hands of a few affluent people or only of academic interest. Almost two decades ago some research was done on developing a sound amplification device to hear the noise of grubs making the characteristic gnawing sounds. After several years of research it was found that the prototype instrument was well short of the expected accuray and failed in field testing.
Some researchers have come out with more sophisticated devices to record the noises produced by the insects inside the stem. Here again these instruments do not meet the basic requirements of accuracy and economic viability.
Till such time a tool is developed for detection, visual checking of suspected palms with a long stick or iron rod is more reliable for this purpose.
The so called detection device should be handy, economical, safe, and above all with very low failure rate especially the early infestations, where the grubs are very small and make feeble sounds. Let us hope for better detectors to be made available in the near future.