474 LEPIDOPTERA. 



near to the thick edge of the whig, there is generally a 

 brown clot. The hind wings are much paler than the others, 

 and have a small brownish dot in the middle. The color 

 of the body is the same as that of the fore wings ; and the 

 legs are ringed with buff and brown. The wings expand 

 one inch and three quarters. The body of the female is 

 grayish or yellowish white ; it is sprinkled on the sides 

 with black dots, and there are two square black spots on 

 the top of each ring, except the last, which has only one 

 spot. The front of the head is black ; and the antennae 

 and the less are rino-ed with black and white. The tail is 

 tipped with a tapering, jointed egg-tube, that can be drawn 

 in and out, like the joints of a telescope. Exclusive of this 

 tube, the female measures about half an inch in length. 

 The eggs are beautiful objects when seen under a microscope. 

 They ai'e of an oval shape, and pale yellow color, and are 

 covered with little raised lines, like net-work, or like the 

 cells of a honeycomb. 



As these span-worms appear at the same time as canker- 

 worms, resemble them in their habits, and often live on the 

 same trees, they can be kept in check by such means as are 

 found useful when employed against canker-worms. 



Probably more than one hundred different kinds of Geom- 

 eters may be found in Massachusetts alone. Seventy-eight 

 are already known to me. Some of these are small, and 

 are not otherwise remarkable ; some are distinguished for 

 their greater size and beauty in the moth state, or for the 

 singularity of the forms and habits of their caterpillars. 

 None of them, however, have become so notorious on ac- 

 count of their devastations as the species already described. 



4. Delta-Motus. (Pi/ralides.) 



The Pyratjdes of Linnrevis are nearly akin to the Ge- 

 ometers. Latreille called them Deltoides^ because the form 

 of the moths, when their wings are closed, is triangular. 



