4 Journal New York Entomological Society. iv..i.viii. 



Cedar oil, 24 hrs., or until the specimen was thoroughly cleared. 



In the process of imbedding, the infiltration must be carefully 

 done. To insure the best results, it is well to get the specimens into 

 the hard paraffin and set them back into the oven for a few hours. 

 This insures a uniform medium for cutting. 



Sections cut from ten to fifteen microns thick gave the best results 

 for the general outline, while for the finer cell structure sections seven 

 microns thick were better. Sections were stained on the slide with 

 hematoxylin and counter-stained with safranin to bring out the chitin. 

 When staining with safranin it is necessary to leave the slides in for 

 at least 24 hours, then differentiate very rapidly, dehydrate, clear, 

 and mount all within a very few minutes. Orange (i. was also found 

 to give good results as a counter-stain for chitin. 



For the study of the wings as a whole it is necessary to dissect 

 them from the body and mount in glycerine jelly ; the jelly must be 

 cooled cjuickly in order to insure the trachea.' not being filled with it. 

 To accomplish this, lay open the larva along the dorsal line and pin 

 the cut edges of the tegument to the wax bottom of a dish, all being- 

 done under water. The wings are recognized as small fiat l)odies a 

 little longer than wide. Figure 12 shows a drawing made from a 

 photograph taken and mounted as above. The dissection of the pupal 

 wings to bring out the tracheae, for the study of the wings as a whole, 

 is nicely brought about by placing the pupa in 4% formal for from 

 six to ten hours ; this hardens the tissues and at the same time leaves 

 the air in the trache;^, which appear as black lines under the micro- 

 scope. 



The First Larval Stace. (Plate I, Figs, i, 2, and 3.) 



The wing-buds are found in the very earliest stages of the lar\al 

 life ; embryos were not examined. Figure £ represents a section 

 through the body-wall of one side of a thoracic segment at a point 

 where a wing-bud is developing ; r represents the cuticle and // the 

 subjacent layer of cells, the hypodermis. The section was taken from 

 a larva which was not more than one-half hour old. At a point op- 

 posite a trachea (Fig. i, /) the cells of the hypodermis are elongated ; 

 these elongated cells constitute the rudiment of a wing or a wing-bud. 

 Rudiments like this of organs that are not to be functional till the 

 adult stage are often termed imaginal discs or imaginal buds. Near 

 the center of the outer surface of this group of cells forming the 



