336 AMERICAN POMOLOGY. 



GEOMETERS, SPAN-WORMS, CANKER-WORMS. 



The measuring worms take their niime from their pecu- 

 liar method of locomotion ; having their legs at each end 

 of their long bodies, they walk by progressive leaps, arch- 

 ing up their backs by bringing their hind-legs forward, and 

 then thrusting their heads out to their full length. Many 

 of them drop from the trees, and hang suspended by a 

 thread of silk, when disturbed, or when seeking the earth 

 to undergo their transformations. Some of them are nak- 

 ed, or have few hairs ; most are smooth, often striped, or 

 of an uniform color, like the bark of the trees on which 

 they feed. 



The moths are slender-bodied ; the wings large ; of some 

 the females have no wings. These are the Hybemians, 

 including the Canker-worm, Anisopterix vernata. These 

 caterpillars are very numerous and destructive ; they do 

 not feed gregariously, and are difficult to combat in that 

 form. The pupae are under ground, and, as the female 

 moths are wingless, and must ascend the trees to deposit 

 their eggs, we can destroy them in the perfect form by 

 meeting them on the highway they have to pass. Ingen- 

 ious devices have been invented for this purpose ; among 

 the most effective of these are vessels of oil, fastened 

 closely around the bole of the tree. The moths emerge 

 from the ground in early spring, but many come out dur- 

 ing pleasant mild days in the winter, and some even in the 

 autumn ; so the remedies must be applied early to be of 

 any use. 



Harris describes a smaller species as the Anisopterix 

 pometaria. 



Hybernia tiliaria. or the Span-worm of the Linden, is 



