254 Destroi/ers of the Trees in St. James's Park. 



degree infected, and every week we may observe that a tree 

 has perished. 



I have taken three different species of coleopterous insects 

 on the elms in the Park, viz. Hylesitius Destructor Latr. , Sco- 

 li/tus ligniperda Latr., and Hypophlecus bicolor Latr. As they 

 are all decorticators, they no doubt all tend to produce the 

 effects we witness ; but as the great criminal is the Hylesbms 

 Destructor^ I shall content myself with giving his history, from 

 which that of the others little differs. 



The Hi^lesinus Destructor is a brown' beetle with a polished 

 black head and thorax, and is in this its perfect or winged 

 state throughout the summer montlis. It appears to confine 

 its attacks in a great degree to the elm, which by the way ought 

 to prevent for the present the planting of any young elms iu 

 the park. When the insect has laid its eggs in the crevices 

 under the bark of this species of tree, it soon dies. The larvge, 

 however, that are hatched from these eggs pierce their way 

 into the wood, and remain there feeding at their ease during 

 the winter. About the end of this season they return towards 

 the surface of the trunk and assume the pupa state, when in 

 spring the first symptom of the disease appears, by the cre- 

 vices of the bark being full of what seems a very fine sort of 

 saw-dust. This results from the continued attempts of the 

 perfect Hylesini on leaving their pupa state to arrive at the 

 external air. The bark indeed is soon loosened from the stem 

 by their endeavours, and at length falls in large pieces, when 

 the leaves turn yellow, wither, and the tree finally perishes ; 

 but not before a new brood of larvae has been hatched to 

 spread further devastation in a future year under the form of 

 winged insects. It thus is evident that winter is the proper 

 time to cut down such dead elms, which ought then to be 

 burned with the larvae contained in them. Hitherto however 

 the time selected for cutting down the dead elms in the Park, 

 has been just after all the mischief for the season has been ef- 

 fected, and when these nurseries of Hylesini have sent forth 

 their inhabitants to the air for the benefit of such trees as might 

 have remained free from infection. Perhaps it may yet be 

 worth while to make the experiment, whether such trees may 

 not be preserved sound and intact by having their trunks 

 coated over at the proper season with some vegetable pitch. 



If these remarks should be of any service towards preserving 

 the ancient appearance of the parks, I shall be glad ; but I re- 

 peat, that I fear it is too late, and that my principal satisfaction 

 in making this communication to you must result from my 

 having " thrown the blame on the right shotddcrs." 



1 am, gentlemen, yours, &c. 



Dendrophilus. 



