THE STATE ENTOMOLOGIST. 95 



resenting them magnified. They are glued together by a grayish var- 

 nish which the mother moth secretes, and they are attached to the 

 trunk, or to some one or other of the twigs of the tree, and may often 

 be found on the inside of loose scales of bark, each batch consisting 

 of upwards of a hundred eggs. 



As the leaves begin to form, these eggs hatch into minute, thread- 

 like span-worms, which in from three to four weeks afterwards ac- 

 quire their full size, when they appear as at Figure 66 c. The Can- 

 ker-worm is distinguished from most other caterpillars that attack 

 the Apple, by having but four prolegs at the end of the body. The 

 normal number of such prolegs in caterpillars, is ten; and it is the 

 lack of the foremost six which obliges our insect to span or loop, 

 from which habit the characteristic name Geometridjs has been given 

 to the group to which it belongs. 



When full-grown this worm measures scarcely an inch in length, 

 and is commonly ash-gray on the back, darker at the side and yellowish 

 [Fig. 67.] beneath. It varies greatly in the intensity of its mark- 

 ings however, ash-gray, green, and yellow ones occur- 

 ring in the same brood, and the most constant character 

 by which it maybe distinguished from other span-worms 

 of the same size, is the pattern of the head, which, 

 j^QV no matter what the general hue of the body may be, is 

 ^■^ usually shaded and marked as in the annexed Figure 67. 

 The markings of the worm vary indeed so much, that, without this 

 criterion I could hardly venture to determine a Canker-worm larva 

 myself. 



I subjoin a very full description of this worm from numerous 

 average specimens, as it is of considerable importance, that an orch- 

 ardist may be able to ascertain definitely whether he is troubled with 

 the true Canker-worm or not. For if he mistakes some other span- 

 worm which produces winged females as well as winged males, for 

 the genuine Canker-worm which is apterous in the female moth state, 

 it becomes very obvious that all his efforts to try and prevent the 

 ravages of the spurious Canker-worm by the most approved and well- 

 tried methods, will not only fail most absolutely, but he will lose all 

 faith in such remedies, and may perchance, if he is given to the use 

 of the quill, vent his wrath and disappointment by sending to some 

 one of the horticultural journals of the land, a pithy article "based 

 upon facts [?] and experience" showing up the utter worthlessness of 

 the Canker-worm remedies ! 



It is from such lack of true knowledge that the City Fathers of Bal- 

 timore, Maryland, went to the useless expense of furnishing oil troughs 

 for all their large elm trees which were being defoliated, under the 

 delusive idea that the insect committing the ravage was the Canker- 

 worm; whereas it turned out to be the larva of a little imported Bee- 

 tle ( Galeruca calmariensis, Fabr.), the female of which has ample 

 wings, and can fly as readily as a bird from tree to tree ; and it is 



