Dec. 1896.] Dyar : Life-Histories OF N. Y. Slug Caterpillars. 1G9 



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 flexiiosal'''' 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 i.o x .6 mm. 

 Laid singly on the under side of the leaf. 



Stage I. — (Plate VI, figs, i 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 

 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 flexuosa. 



