OAK LEAF-ROLLER. 
61 
June), when our night temperature had been at 84°, that I first 
observed the caterpillars falling off in large numbers.” 
This observation of moth-caterpillars being destroyed by sudden 
wet quite corresponds with what was noticed by Curtis in his ‘ Farm 
Insects ’ many years ago ; and more recently by Mr. E. A. Fitch, Hon. 
Sec. of the Royal Entomological Society, on occasion of the great 
appearance of the Plusia gamma , the Silver-Y or Beet Moth, in Essex 
in 1879 (see my Report for that year, p. 5). 
This peculiarity has not, so far as I know, been utilised as yet as a 
means of getting rid of caterpillar-attack, but, however it may be 
in field cultivation, it would be worth trying (where there is an 
available water supply laid on for garden use) whether good drenchings 
through a hose might not clear the obnoxious presence of caterpillars 
on Cabbage. 
One of the trees attacked in Sir H. Yerney’s park being of especial 
value, on account both of its great age and size, it was wished to 
restore the foliage as soon as possible, and likewise to clean the tree 
from any remains of attack, and from other insects, as Aphides, &c., 
which might have remained. I therefore advised thoroughly washing 
down the tree by means of the house fire-engine, throwing the water, 
not broadcast amongst the boughs so as to tear or bruise any young 
leafage that was beginning to appear, but sending it directly at the 
trunk and large boughs. In this way the stream of water was thrown 
about in spray amongst the twigs, and thoroughly moistened every 
part, whilst the stream directed against the trunk cleaned out much of 
the insect-vermin that might be present. The ground beneath the 
tree was so well moistened as to help the coming growth greatly. 
A few weeks after the experiment Mr. Sharp reported that:— 
“ Through the soaking which we gave the tree has recovered its 
foliage wonderfully. On all the parts on which we were able to play, 
the Aphides and all other insects, as far as I can discern, are cleared 
off, and I have no hesitation in saying that it is the right thing to do 
where trees are attacked, a fire-engine kept, and water at command.” 
On the 20th of August, Mr. Sharp further reported that it was 
wonderful to see how well the tree was then furnished with leaves. 
One cannot always have the necessary amount of water nor engine- 
power at command; still, the above experiment may be of service in 
showing the benefit of applying measures to induce luxuriant growth ; 
and in some cases like the above, where it is an object to preserve 
trees some centuries old from the results of devastating attack, the 
operations might be similarly carried out. 
