THE FOUR- HORN ED CERATOMIA. 
323 
] el , ( .th of five or six inches, but, when not in use, is coiled 
like a watch-spring, and is almost entirely concealed be- 
tween two large and thick feelers, under the head. 
Among the numerous insects that infest our noble elms, 
the largest is a kind of Sphinx, which, from the four short 
horns on the fore part of the hack, I have named Ceratomia * 
quadricornis (Fig. 148), or four-homed Ceratomia. On 
some trees these Sphinges exist in great numbers, and their 
ravages then become very obvious ; while a few, though 
capable of doing considerable injury, may escape notice 
among the thick foliage which constitutes their food, or will 
only be betrayed by the copious and regularly formed pellets 
of excrement beneath the trees. They are very abundant 
during the months of July and August on the large elms 
which surround the northern and eastern sides of the Com- 
mon in Boston ; and towards the end of August, when they 
descend from the trees for the purpose of going into the 
ground, they may often be seen crawling in the Mall in 
considerable numbers. These caterpillars (Fig. 149), at 
this period of their existence, are about three inches and a 
# Ceratomia, derived from the Greek, means having horns on the shoulders , a 
peculiarity which I have not observed in any other Sphinx. 
