POPLAR CATERPILLARS. 445 
escape which it carefully guards by means of a silken membrane re-enforced by frag- 
ments of wood ; it then lines its burrow with silk and spins a firm cocoon about 
itself. 
Kellicott calls attention to the very close mimicry of this moth after 
certain wasps, seen in the form and color of the moth, its markings, 
as well as its motions and attitudes. 
Larva. — The larvae, when taken, April 15, were of two distinct sizes, the larger 
measuring from .9 to 1.1 inch in length, the smaller .5 inch and less. The former 
appeared to increase but slightly before pupation. Dull white with a darker line 
along the back; head quite strongly bilobed, light brown, jaws and clypeus black ; 
the first ring smooth, slightly clouded with brown, two irregular oblique marks from 
the posterior border outwards to the front edge. Body somewhat attenuated toward 
either end ; transverse wrinkles, especially on the thoracic rings, well marked ; in 
the small ones there is a slight medio-dorsal indenture ; there are also lateral snb- 
stigmatal wrinkles. Stigmata elliptical, brown, last pair large, placed subdorsally 
and posteriorly. Above the anal feet, directed backwards, there are two black 
chitinous teeth; in the younger specimens they are more prominent and upturned. 
The scanty brown hairs arise from slight papillae. 
Pupa. — Light brown. The clypeus is armed with a sharp wedge shaped process, 
strengthened by ridges at its four angles and also by a median dorsal ridge. The 
abdominal rings are furnished, as usual, with two transverse rows of teeth, except 
the anal and pre-anal segments, which have but one row each. The terminal ring 
is obliquely truncated, having several teeth. Length, .6 inch. (Kellicott.) 
Moth. — Blue-black ; fore-wings opaque ; hind wings transparent, with the border, 
fringe, and transverse line near the middle black ; palpi at tip, collar, a spot on each 
shoulder, and three bands on the abdomen yellow ; antennae short, black ; the four 
posterior tibiae banded with orange; tarsi yellow, tipped with black ; tail flat, with 
two longitudinal yellow lines. Expands from I to 1£ inches. (Harris.) Kellicott 
adds that the male is considerably smaller than the female, the antennae strongly 
pectinated to the apical portion, which is enlarged and hairy. The abdomen has 
four yellow bands and there are no " longitudinal yellow lines in the tail." Both 
sexes have a conspicuous white spot bordering the eye in front ; four small yellow 
spots on the upper part of the thorax ; two below the base of fore- wings, also a 
yellow line at the outer edges of the collar; the outer edge of the coxae of the first 
pair of legs, also those of the second and third pairs,are of the same color. The fore- 
wings are more or less washed with red on the basal third. The second abdominal 
band alone appears on the ventral side ; in front of it below is a yellow line. 
AFFECTING THE LEAVES. 
11. The stout poplar span worm. 
Biston ursaria Walker. 
Order Lepidoitera; family Phal^nid^:. 
In some seasons, during July, partially defoliating the Lombardy poplars in Mon- 
treal, Canada, large drab or dingy purple span worms, at the end of July burying 
themselves in the earth, the moths appearing during the last week in April and the 
early part of May. 
According to Mr. G. J. Bowles (Gau. Ent., viii, p. 7) this span worm 
abounds year after year ou the Lombardy poplars in the city of Mon- 
treal. " In some seasons the trees are partially defoliated by the larvae, 
