56 



only treatment available. Thereafter, however, other methods for 

 their control are preferable and should be made use of. 



The fact that tiie females lay their eggs on the twigs ; that they 

 come from the ground ; and that being wingless, their only way of 



reaching the twigs is by crawling up the 

 trunk, point to the treatment, which is 

 to band the trunks of the trees with an 

 adhesive such as Tree Tanglefoot. This 

 should be applied in September for the 

 fall canker worm and be kept fresh until 

 winter, one application usually being 

 sufficient. For the spring canker worm, 

 the tanglefoot should be applied on the 

 first warm day — sometimes in February, generally in March — and 

 be kept fresh until the middle of May. If this treatment be care- 

 fully made, no trouble from canker worms need be feared. 



Fig. 6. Spring canker worm, 

 a, full-grown caterpillar ; b. en- 

 larged egg and part of a mass, 

 natural size ; c, d, structural de- 

 tails. 



SPRUCE GALL LOUSE. 



{Chermes abietis L.) 



This tiny plant louse forms galls at the bases of the twigs of vari- 

 ous kinds of spruces and seriously injures the trees. Old, dry galls 

 with open cavities in them remain on the tree for years after they are 

 formed and the new ones, which are green, occasionally with pinkish 

 marks, appear in June and July. In these galls the lice feed until Au- 

 gust, when the galls begin to turn brown and the cavities within crack 

 open, allowing the insects to escape. During the remainder of the 

 year, the insects in various stages may be found on the tree but are 

 not in galls. 



The formation of a gall at the base of a twig almost always results 

 in the death of that twig, so that when these insects are abundant 

 the tree, instead of being thickly covered with foliage, becomes thin, 

 with many dead twigs, and, as a whole, is far from being the orna- 

 ment it should be. 



There are two methods by which the attacks of this insect may be 

 reduced. If the tree has only recently become infested, the galls 

 will be few in number, and may be picked off and destroyed during 

 June and July. If they are too abundant for this to be practicable, 

 spraying very thoroughly in April with one pound of whale-oil soap 

 dissolved in two gallons of water has proved effective. 



