THE LARGE LARCH SAWFLY. 151 
Though in recent years attacks by this insect have been 
recorded in England, Scotland, and Wales, it is perhaps in the 
English Lake District that the most serious damage has resulted. 
Some account of the attack there and the methods resorted to in 
order to combat it will now be given. It has been stated that 
harm was done in the district by this insect in 1868, but the 
identification was not reliable. The present attack was first 
observed in 1904, more seriously in 1905, and in 1906 the cater- 
pillars were satisfactorily identified as being those of the Large 
Larch Sawfly. Apparently the centre from which the pest 
spread was the Dodd Wood, which is about four miles from 
Keswick, in the Bassenthwaite direction. Thousands of trees 
are stated to have died there; they varied in age from twenty to 
seventy years. In the past two years I have found the insect 
present in widely spread localities in Cumberland and West- 
morland—in fact, wherever I have searched for it this Nematus 
has been found present. The strength of the attack varies 
greatly in different portions of the area. As might be expected, 
pure larch-woods suffer more severely than those in which other 
kinds of trees are mixed with the larch. Trees which have been 
attacked by the Large Larch Sawfly may be recognized by their 
terminal shoots being withered and brown, and curled towards 
one side (that on which the sawfly has deposited her ova). 
This withering is practically invariable, but I have met with 
a case in which some very vigorous English and Japanese 
larches showed no sign of it, though the shoots had all 
suffered from the attacks of the sawfly. These trees were 
about seven years old, and better specimens I have not 
seen; no doubt their exceptional vigour enabled them to 
withstand the attack more successfully than is normally the 
case. 
When the attack is really severe the tree is defoliated, all the 
sreen growth, with the exception of the shoots of the year, being 
devoured by the caterpillars. The larches then present practi- 
cally the same appearance that they do in mid-winter, and 
woods attacked as severely as this have a brown appearance, 
which is easily recognisable at a distance of several miles. In 
August these trees put forth a fresh flush of foliage, and present 
the appearance more usually associated with spring. In the 
