Dec. 1896.] Dyar : Life-Histories of N. Y. Slug Caterpillars. 169 
the same plant. The larva remains on the back of a leaf, where its 
shape and coloration are adapted to its concealment. 
The material from which this life history was worked out was col¬ 
lected by me in stage I at Keene Valley and the eggs found at Bellport, 
Long Island. Miss Morton endeavored to obtain fertile eggs from some 
cocoons which I sent her, but was unable to do so. I am indebted to 
Mrs. Knopf for assistance with the plate. 
Criticism of Previous Descriptions. 
This larva remained undescribed till very recently. In my orig¬ 
inal description I say “the usual elliptical depressions hardly distinct.” 
This may be corrected by omitting the word “hardly.” Miss Morton 
first described the eggs. She says they are “without form,” though I 
should describe them as regularly elliptical and greatly flattened. I do 
not find them “ invisible to the naked eye on the leaves ” since I have 
found them in the woods without the aid of a lens. Dr. Packard’s de¬ 
scriptions seem to contain but one error, besides the inaccurate nomen¬ 
clature, for which I am partly responsible. His “ young larva of 
Heterogenea, sp.” is stage VI, and his “full-grown larva of Hetero- 
genea testacea” and “larva of Heterogenea jlexuosal ” are stage VII 
of T. pallida. The “full-grown larva of Heterogenea, sp.” is another 
insect.* The error referred to is on page 105, where Dr. Packard says 
“there is a median dorsal row of impressed rounded warts, which do 
not bear bristles . . . ”. I think it is evident that these structures are 
the glandular centers of the dorsal depressed spaces, and have no ho¬ 
mology, or even analogy with warts. 
Description of the Several Stages in Detail. 
Egg. —Elliptical, flat, transparent on smooth green leaves, whitish 
■ translucent on whitish leaves, shining; reticulations faint, visible in a 
strong side light under a half inch objective as narrowly linear elongate 
hexagonal lines, slightly more opaque than the shell. Size 1.0 x .6 mm. 
Laid singly on the under side of the leaf. 
Stage /.—(Plate VI, figs. 1 and 2) Elliptical, rather elongate, dor¬ 
sal and lateral spaces rather broad. Along the subdorsal ridge, a row 
of Y-shaped setae with expanded cleft tips, changing to two separate 
t setae on joints 3 and 13 ; two lateral setae on joints 3 and 4; along the 
lateral ridge a row of single swollen-tipped setae on joints 3 to 12. 
* Doubtfully identified Journ. N. Y. Ent. Soc. Ill, 146, as Heterogenea ftexuosa. 
