Plant Sanitation. 



492 



[Dec. 1906, 



Entomological Notes. 



By E. Ernest Green, Government Entomologist. 



In a valuable paper on 'The Principal Insects Attacking the Coconut Palm,' 

 by C. S. Banks, published in the Philippine Journal of Science, Vol. 1, Nos. 2 and 3, 

 mention is made of a native treatment employed against the attacks of the Rhino- 

 ceros beetle. This consists in placing sand and coarse salt in the crown of the tree. 

 "The Filipinos state that the sand gets between the articulations of the head and 

 thorax of the beetle where the constant friction sets up an irritation which even- 

 tually punctures the soft tissues, after which the insect dies.' During a recent 

 visit to Trincomalie, I was interested to find that a similar theory is maintained by 

 the local coconut growers. The practice seems to be a sound one, and. it might be 

 employed with particular advantage on all young coconut estates. Besides the 

 placing of sea sand in the crown of the tree, no better material could be employed 

 for filling up the holes after the extraction of the beetles. The loose gritty sand 

 prevents the inoccupation of the holes by other beetles— either Rhinoceros or Red 

 Weevil, 



A new species of Shot-hole-borer has been noted. It has, at present, been 

 observed only in a single tea nursery, and immediate steps for its eradication were 

 taken, by the cremation of all the plants. The insect is a Scolytid beetle, very 

 similar in appearance to Xyleborus fornicatus, but considerably smaller in size, 

 The following measurements will give an idea of the comparative sizes of the two 

 species : — 



Xyleborus fornicatus, length of female 2'25 millimeters ; 



male 1*50 do. 

 Xylebor us (new species), do. of female T75 do. 



do. male 1 do. 



There are other minute distinctions which can be detected only by the aid of 

 a, microscope. The point of attack is near the ground, just above the collar of the 

 plant. The galleries run longitudinally up and down the pith of the plant, with a 

 single transverse circular gallery at the point of entry. They appear to be more 

 densely crowded with insects in all stages than are those of X. fornicatus. In every 

 case the plant had been killed at the point of attack, the root remaining healthy 

 and the upper part of the stem often still green (in cases of recent attack). 



If unchecked, this insect mighc possibly become a serious pest. Owners of 

 tea nurseries should be on the watch for its appearance. In the event of its 

 occurrence, no half measures should be permitted ; but the whole nursery should 

 be sacrificed. 



We have always been led to suppose that camphor wood was immune to 

 insect attack. But our confidence is apparently misfounded. I have recently 

 received specimens of camphor branches attacked by a Scolytid beetle, distinct from 

 but apparently allied to the ' Shot-hole-borer ' of the tea plant. The insect perforates 

 branches of over one inch, down to twigs of less than a quarter inch in diameter, 

 The bark, for some distance above and below each point of attack, is discoloured 

 (deep brown). The discolouration penetrates into the wood. In deserted galleries— 

 in the larger branches— the central woody area is dead and decayed, but the bark 

 appears to have recovered and to be carrying on its normal functions. Smaller 

 branches are often killed outright. The galleries of the insect are transversely 

 circular and restricted to that one point. They do not run up or down in the branch, 

 The beetle has a bright reddish head and thorax, with the hinder parts (abdomen 



