182 Annals E^itomological Society of America [Vol. IX, 



Eggs are laid in a definite cluster on the lower surface of the 

 leaf and very near the margin. No egg masses were found in 

 connection with punctures or artificial breaks through the 

 leaves. The eggs are arranged in concentric rows, usually four, 

 which are separated by uniform spaces, each row being curved 

 so that the concave side is always towards the margin of the 

 leaf. The number of eggs composing the clusters examined in 

 this connection varies from 17 to 76. Clusters are sometimes 

 placed so closely together that they appear to be almost con- 

 fluent. The row of eggs nearest the margin of the leaf is always 

 at least 2 mm. from the edge and sometimes as much as 5 mm. 

 Oviposition was not observed but the position of the egg mass 

 and the distance of the rows from the edge of the leaf indicate 

 that possibly the female lays the eggs, in a manner similar to 

 that suggested for N. maculalis, by clinging to the edge of the 

 leaf, extending the ovipositor under the edge and swinging it 

 around, thus depositing the eggs in concentric rows. 



Description. — The eggs are elliptical in outHne, slightly 

 flattened, smooth, uniform in size, and 0.45 mm. x 0.6 mm. in 

 dimensions. They are whitish in color, being distinctly lighter 

 than the leaf surface on which they are placed. When first laid, 

 they show no external signs of internal differentiation. 



Development. — The egg period is from ten to eleven days. 

 Eggs, deposited in the aquaria, develop in the same way and at 

 the same rate as the egg masses collected in the field. During 

 the first two days subsequent to oviposition, no internal changes 

 are evident. At the end of about fifty hours, the eggs begin to 

 show signs of internal differentiation and, during the following 

 24-36 hours, a dark band develops within, similar in some 

 respects to the one which appears in the early development of 

 the eggs of N.. maculalis. This band has a shape somewhat like 

 the letter J and is constant in its position in all of the eggs, the 

 more curved end of the band being invariably in the end of the 

 ■egg remote from the edge of the supporting leaf. After five days 

 of development, the dark band has increased considerably in 

 size and has changed somewhat in shape, showing distinct 

 differences in the two ends, one being larger and more blunt 

 and recognizable as the future head of the caterpillar. During 

 the seventh to the ninth day, the black areas on either side of 

 the head appear and the longitudinal tracheae are visible. The 



