452 



The Genus Chermes. 



[sept., 



Spruce galls, it is the side-shoots, and not the leading shoots, 

 which are spoilt. 



2. Larch. — The needles become bent, owing to the sucking 

 of the Chermes, and the apical portion of the infested needles 

 may wither away, and the bark is also punctured. When the 

 pest is abundant, the trees must suffer in health. It is young 

 Larch which is attacked, and two quotations may be given 

 from correspondents to show the possibilities of damage : 

 "The Larches are now 15 ft. high, but during the past three 

 years a considerable number have died off; the foliage gradu- 

 ally withers up, and eventually the trees become quite dead. 

 Twigs and bark are covered by the deposit." "Larch of 

 eleven years of age is dying with the white on stem and 

 branches." 



The indirect damage owing to the following on of other 

 enemies also deserves notice. Specially interesting in this 

 connection is the possibility of infection by the spores of the 

 Larch-disease fungus (Dasyscypha calycina). 



The Larch-disease fungus is a wound parasite, the fungus 

 mycelium from the germinated spores entering the tissue of 

 the trees by some kind of wound. Burdon's dissections have 

 satisfactorily proved that one such kind of wound for afford- 

 ing entry to the fungus is that made in the bark by the 

 proboscis of the Chermes. Massee * had previously suspected 

 this mode of entry, and as a result of experiment he wrote : 

 " I have repeatedly produced Larch Canker by placing asco- 

 spores underneath the foundress." Further, a Chermes- 

 infested tree is physiologically weakened, and is thereby less 

 capable of resisting the fungus. 



3. Abies. — Here, too, the needles may show curvature, and 

 become brown and die. Shoots are also infested, and this, 

 with attack on young shoots and older bark, results in the 

 falling off and, it may be, ultimate death of the plants. 



4. Pinus. — The same loss of health attaches to the 

 Chermes infestation on dwarf shoots, and the bark of twigs 

 and stem. 



Treatment. — 1. If removal of the galls on the Spruce be 

 attempted, it ought to be practised when the plants are 

 young, and should be done thoroughly. In a garden, at 



* Journal of the Board of Agriculture, Vol. IX, Sept. 1902, p. 180. 



