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The actual accumulation for any date during different seasons may 
_ vary widely from the normal accumulation. 
a By comparing the actual accumulation at any date during a given 
season with the normal accumulation for that date, the approximate 
number of days which development has been retarded or hastened on 
that date may be determined; and, by keeping track of the number of 
effective day-degrees that accumulate as the season advances, one may 
foretell, approximately, several days in advance, the dates when the 
larve of the different generations will begin to enter the fruit. 
EQuIPMENT AND Metuops oF WorK 
Aside from the large cages and the weather instruments previously 
mentioned, cages were devised for observing pupation of larve, emer- 
gence of moths, oviposition, and length of life of adults. 
For observing pupation, cages such as those illustrated in Figures 
1 and 2, were found to be most satisfactory. They consisted of two 
blocks of wood and a strip of celluloid, each 434 inches long and 2% 
inches wide. On the face of one of the blocks, strips of wood or heavy 
paper about ¥% inch thick were tacked along the end and longitudinally 
through the middle of the block, to hold the blocks far enough apart to 
permit the larve to crawl in between them. A strip of corrugated straw- 
_ board split through the middle so as to leave half of the corrugations on 
each face was placed, with the split surface up, on the block on each side 
of the center strip so as to cover the remaining face of the block. The 
_ other block was placed on the top of this with a strip of celluloid between, 
and the blocks were held together by small hooks and eyes fastened to 
the edges of the block, or by rubber bands—the latter proving the more 
satisfactory. There was room in each cage for about 50 larve. Smaller 
- cages for single larve or a small number: of larve were made on the 
same principle without blocks of wood. 
When it was desired to determine the dates of pupation of larve 
collected from bands, they were confined in a lantern globe with one or 
more of the larger pupa-cages. Thus enclosed, the larve crawled into 
the little cells and spun their cocoons, and were thus arranged in very 
convenient order for further observation. By the use of sandpaper, the 
celluloid was roughened longitudinally through the center of the block, 
and after the larve were settled the number of each was entered on the 
_ celluloid beside it. (Fig. 2.) 
Usually, transforming larvze spun so thin a web on the exposed side 
_ of the cocoon that pupation could be observed without disturbing them, 
‘but hibernating larvee spun a thicker web, and to observe them it was 
necessary to tear away a part of the web next to the celluloid every time 
an observation was made. The most convenient instrument for doing 
‘this was a steel crochet-needle with the hook ground away so as to leave 
only a small part of the barb. The cages above described will be referred 
_to as pupa cages. 
