3 



10. Effects on Vegetation. -The caterpillars damage the trees 

 by eating their leaves, commencing on the old leaves, and when 

 these are consumed going on to the younger ones. When the 

 trees have been entirely denuded of leaves, they are practically 

 dead, as leaves are the principal organs where the conversion 

 takes place of various inorganic substances into organic matter, 

 for the food and building up of the plant. There are very few trees, 

 however, which have lost all their leaves, and these few are located in 

 various parts of the Island. There are some around Aberdeen, at Deep 

 Water Bay, at Causeway Bay and North Point at Shaukiwan and near 

 Chaiwan. Many trees have been stripped of -their old leaves and are 

 consequently in a rather sickly condition. I am of opinion, however, 

 that they will recover in time, as most of them have sufficient young 

 leaves to enable them to make new growth, in fact, a good number of 

 them are already starting to grow. 



11. Previous Visitations —If the Chinese are to be believed, this 

 caterpillar has been known on the mainland for several years past, 

 and the natives regarded it as an annual visitor with no very great 

 destructive powers. A few leaves were eaten yearly, but no practical 

 damage done. It was not observed in this Colony until the end of the 

 summer of 1892. Little damage was then done to the trees, which may 

 be explained by the fact that the number of insects was comparatively 

 small, only two or three being seen on each individual tree. The lo- 

 calities which they appeared in were Deep Water Bay and Kowloon. 



12. The second appearance was last year, at Quarry-Bay and Kow- 

 loon, towards the end of July. Their numbers had very much increased 

 on the previous year's, as twenty, or thirty were sometimes found on a 

 single tree. At Quarry-Bay upwards of 30,000 trees were killed, as 

 the Chinese from various reasons couH not be induced to collect the 

 pest. One of the chief objections to take part in the work was the pain 

 caused by the hairs of the caterpillars stinging their hands and feet, as 

 well as other parts of their bodies. Another objection was the great 

 difficulty in finding the insects after they had fallen amongst the long 

 grass underneath the trees. Great numbers were collected by our own 

 staff, but owing to the unhealthiness of the district the men had to be 

 taken away, and, as it was, two of the men died from fever contracted 

 whilst at work in that neighbourhood. 



13. Probable cause of Plague — The cause of the very greatincrease in 

 the number of the insects this year on anything previously known is in my 

 opinion, as follows. The winter of 1892-93 was exceptionally severe, and 

 it is quite probable that the natural foe of the caterpillar succumbed to the 

 extraordinarily low temperature. What its enemy is, or was, so far has 

 not been discovered, but no doubt one existed. This idea is very much 

 strengthened by looking at the colour and marking of the caterpillar. 

 When it is full grown its colour closely resembles that of the Pine tree 

 branches, and its markings correspond with the scars left on the branches 

 after the leaves have fallen away. On account of this, in examining Pine 

 trees, it is most difficult to see the caterpillars on them, until the trees 

 have been very closely scrutinised for a few minutes ; this too when the 

 caterpillars have attained their maximum size, nearly three inches in 

 length and a quarter of an inch in breadth. This close resemblance to 

 the branches of the trees on which these insects thrive, undoubtedly 



