EXTERMINATING NOXIOUS INSECTS. 233 



tion in color is common to most other span-worms. Pro- 

 fessor Riley once stated that the word canker-worm has 

 formed the heading of so many articles in Agricultural and 

 Horticultural journals, during the last ten or twelve years, 

 and its natural history has been so fully given in the stand- 

 ard work of Dr. Harris, that one almost wonders where 

 there can be a reading farmer who does not know how 

 properly to fight it. But we must remember that new 

 generations are ever replacing those which pass away, so 

 that the same stories will doubtless have to be repeated to 

 the end of time. Facts in Nature will always bear repeat- 

 ing. Hence, as it may be laid down as a maxim that no 

 injurious insect can be successfully combated without a 

 thorough knowledge of its habits and transformations, we 

 will first recount those of the Canker-worm, and afterwards 

 state the proper mode of extermination. 



The figures herewith given represent a full-grown Can- 

 ker-worm, and the same pest in its different stages. The 



Fig. 86. Fig. 87. Fig. 88. 



Larvae of the Canker- Miller of the Canker- Female moth of the 



worm. worm. Canker-worm. 



eggs of this insect are very minute, short, and cylindrical, 

 and are deposited close together in rows, forming batches. 

 They are glued together by a grayish varnish which the 

 mother moth secretes, and they are attached to the trunk, 

 or to some one or other of the twigs of the tree, each batch 

 consisting of upwards of a hundred eggs. As the leaves 

 begin to form, these eggs hatch into minute, thread-like 

 span-worms ; and in from three to four weeks afterwards 



