THE UNICORN WORM. 269 



this Hue and the outer margin is a faint band. Between the two principal lines are 

 some black scales ; a fen^ black scales mark the obsolete discal spot. Towards the 

 apex on tie costa are four dark spots. Hind wings smoky, a little discolored at the 

 internal angle, beneath concolorous. The female wants the few black scales between 

 the two principal lines. Length of body, male, .70 ; female, .75; expanse of wings, 

 male, 1.50; female, 1.50 inch. 



THE UNICORN WORM. 

 39. Schizura unicornis (Abbot and Smith). 



The caterpillar of this moth, more commonly met with on the apple 

 tree, we have found September 6 on the elm at Brunswick, Me. At 

 about this date, Harris says, it makes its cocoon, which is thin and al- 

 most transparent, resembling parchment in texture, aod covered gen- 

 erally with bits of leaves on the outside. The caterpillars remain in 

 their cocoons a long time previous to changing to chrysalids, and the 

 moth appears the following May and June. 



This and the other species of the genus are doubtless protected from 

 the attacks of birds by their close resemblance to a dead, dry portion 

 or blotch on the edge of the leaf, as they usually feed on the edge. 



The following observations have been made by Professor Riley : 



The larva of the above species is found feeding on quite a number of different 

 plants, such as oak, elm, plum, apple, dogwood, alder, winterberry, rose, and black- 

 berry, also on hickory. 



It is a very singularly shaped caterpillar. General color in sound specimens, rich 

 reddish-brown, in others grayish-brown, shaded with very minute spots of a darker 

 <;olor, which give it a shagreened appearance. A faint line of a darker color runs 

 along each side from the third segment. It is variegated on the back with a lighter 

 color, somewhat in the shape of a letter yy/ as one looks from the head, and two lines 

 forming a V start. 



Larvte found on blackberry were mostly very pale, with the white Y mark on 

 joints 9 and 10 very plain, with much glaucous coloj; about the back, and with the 

 other shades of pnrple-brown, flesh-brown, olive and pale green, which are found on 

 the withering blackberry bushes, all present. The glaucous and brown colors are 

 especially noticed on the canes of this plant. 



The insect is evidently two-brooded, those of the first brood spinning up at the 

 commencement of July, while iarvje of a second brood, often only about one-fourth 

 grown, are found as late as October 10, 



The cocoon is very thin and looks much like parchment. It frequently draws a 

 few leaves together for this purpose, and changes to a chrysalis in about four days, 

 which is at first of the same color as was the caterpillar, the green segments being 

 <li8tinctly visible, but soon changes to a shiny brown, with two points at the tail, and 

 one blunter one at the head. There are also slight elevations on the under part of 

 the abdomen where the prolegs of the caterpillar were. 



The mimicry of the larva when on the blackberry, either stem or leaf, is perfect, 

 and the imitative resemblance of the moth, when at rest, to the bark of a tree is still 

 more striking. The moth always rests head downwards with the legs all drawn to- 

 gether and its wings folded round the body, which is stretched out at an angle of 

 about 45 degrees, the dull gray coloring of the wings with the lichen-green and flesh 

 color giving the whole such a perfect appearance to a piece of rough bark that the 

 deception is perfect. 



Some of the larvae are, however, infested with Tachinids and with Opliion purgator 

 Say. (Riley's unpublished notes.) 



