68 THE FAILURES OF THE LARCH. 



and notably in those at the Murthly station, where young blight- 

 stricken larches are maintaining a hopeless struggle with Scotch 

 firs. 



It is now nearly forty years since my attention was attracted to 

 a large break of two-year transplanted larches in the vicinity of 

 Edinburgh, where nurseiy crops have long been supplanted by 

 dwelling-houses. Early in the summer, two small circular patches 

 appeared where the foliage presented a whitish tint. Both of 

 these patches increased in size and whiteness, till the presence as 

 well as the effects of larch bug was unmistakable, even when 

 viewed from a considerable distance, each patch being whitest in 

 the centre, and shaded off to clean, healthy green, at its circum- 

 ference. In autumn the diminution in growth of the plants in 

 both was proportionate to the whiteness, being shortest in the 

 middle, and rising gradually to their junction with the surround- 

 ing uninfected plants. Just before the falling of the leaves, the 

 centres presented a brownish, withered-like appearance ; and 

 throughout the winter a shaded-off blackness held the place of the 

 former whiteness. In the succeeding summer those indications 

 became much extended, as well as intensified, each of the patches 

 widening to about 20 yards in diameter, while the plants in their 

 centres made very short growth, and these around the circular 

 margins remained clean and healthy. Since the period here indi- 

 cated, continuous as well as extensive observations of nursery 

 larch crops throughout the kingdom have still furnished me with 

 more distinctive evidence than the above of the regular and rapidly 

 progressive spread of the bug over previously healthy young larch 

 plants. And these observations have further shown that while 

 no nurseiy visited was entirely clear of this plague, its virulence 

 among many of the older transplants showed that the fire was 

 the only proper place for them. 



After larches have suffered from late spring frosts, the bugs 

 often become so conspicuously abundant as to induce the unten- 

 able notion that they have been produced by the frost ; while that 

 injuring agent may only be blamable for more fully exposing and 

 concentrating them by its partial removal of their leafy covering, 

 and limiting of their feeding ranges, by its restricting or stunting 

 the growths of both the young shoots and foliage. 



It is a very common notion that weak and unhealthy plants are 

 the most susceptible of injury from insects. The insects are, 

 however, much more frequently the cause than the effect of such 



