LXXII GUNNAR SCHOTTE. 
The terminal buds and the flower buds are attacked by a gall-midge, Ceci- 
domyvia Kellneri, not yet recorded from Sweden. 
The insects attacking the needles are undoubtedly the most important of 
the enemies of the larch and the only ones known to be serious pests. The 
most dangerous of these is Nematus Erichsoni, which is distributed over Northern 
Europe, as well as in Canada and the United States. It is recorded from Skåne, 
Småland, Dalecarlia, and AÄngermanland, but has only on two occasions done 
injury, in the neighbourhood of Marma in 1893 on twenty-five-year-old larches 
and at Orsa in 1911. 
On younger larch-trees Nematus laricis occurs: it injured in 1911 10-year 
old larches at Stjärntorp, Östergötland and in 1916 at Gammelkroppa 7-year- 
old larches. 
Amongst the moths there are two enemies of the needles, the most im- 
portant of which is Coleophora laricella; the other being Steganoptycha dimana. 
The latter has hitherto only been recorded from Upland and Norrbotten. 
'The needles are also injured by two plant-lices, Chermes abietis and strobi- 
lobius, and a spinning mite, Paratetranvchus unungurs. 
On pages 676—691 are described the fungus injuries to the larch. The 
most important of these is the larch canker, Dasyscypha Willkommi. "This 
occurs in the native home of the larch and is found everywhere, as a rule, 
where the larch is cultivated. -It has been believed that the canker has 
spread more and more of late, and that it has increased with the extended 
culture of larch. It has also been maintained, for instance in Germany, that 
it spreads more and more the further north one goes. This is shown by 
giving the date when it has been observed in different places. "Thus, ac- 
cording to BEcK, (536 6), the larech-canker was observed in Germany as early 
aAstT840==-50 — Jin Brunswick in 1845 and in EFlessefinkrssoaterfungtbe 
Spessart, in the Thiäringen Forest and in the Hartz, and not till 1880 in East 
Prussia. Attempts have also been made to determine the point of time when 
it spread to England with a consignment of plants. The present author does 
not give much credence to all these statements: <Certain it is that the canker, 
as a rule, has always been found where the larch occurs. 
The fact that the larch-canker has not been heard of until recently is 
assuredly due not to the fact that it has not existed, but to the fact that 
insufficient attention has been given to it. The present writer has found this 
to be the case in Sweden, where, for instance, larch woods have been declared 
on inquiry to be free of canker, but on closer examination they are almost 
always found to have been attacked. The writer has also observed, in 
Skåne amongst other places, old healed canker wounds in older larches, which 
indicate the occurrence of larch-canker at a date before that at which, ac- 
cording to the above-mentioned theory of its spreading, it reached Sweden. 
The present writer has found larch-canker as far north as Medelpad in the 
north of Sweden. 
After an account, on pp. 685—0689, of the precautionary measures which 
have been recommended, specially in England, against the canker, the present 
writer maintains, from this point of view also, the importance of heavy 
thinning. E 
It is, moreover, a matter of general experience that mixed woods are less 
exposed to infectious diseases, as a rule; and the sample plots of the State 
