8 BULLETIN 1051, U. S. DEPARTMENT OF AGRICULTURE. 



Cedar Chests Do Not Kill One-Half to Full Gkown Labv^. 



Cedar chests can not be depended upon to kill larvae after they are 

 half to full grown, or after they are about three or four months old. 

 To be sure, many of these older larvae die in the chests, but it is not 

 possible to tell whether their death is caused by the chests or is the 

 result of the high mortality obtaining among any lot of clothes-moth 

 larva? used in experimental work. The only work done indicating the 

 effect of cedar chests upon the older larva? is that of Scott, Abbott, 

 and Dudley (17) . They say : 



In 1915 flannel was placed in this chest, and 10 one-half to three-fourths 

 grown larvae were added every two weeks until a total of 60 was reached. Ex- 

 amination made two months after the last addition of larvae showed 7 live 

 larvae ; 36 larvae had died and 17 had pupated. Of the 17 pupae 2 died in the 

 pupa stage and 15 emerged as moths, but died before any eggs were laid. The 

 flannel had been fed upon considerably, but was not badly eaten. 



Two years later (1917) this experiment was duplicated by adding 25 one-half 

 to three-fourths grown larvae at one time and allowing the experiment to run 

 33 days. The results were almost identical with those of the first experiment. 



On January 31, 1921, 24 well-grown larva? were placed in a chest 

 upon a high-grade blue-serge cloth, and 35 others upon a felt pillow 

 top. Both lots of larva? caused serious damage to the goods by March 

 2 (PL II, fig. 2). During an examination made on that date it was 

 found that of the 50 larva? 18 were still in the larva stage and alive, 6 

 had died, 9 had transformed to the pupa stage, and 13 had emerged 

 as adults; the remaining larva? had eaten through the cloth and es- 

 caped into the clothing filling the chest. 



Of 100 larva? (40 well grown, 40 half grown, and 20 very small, 

 but fully four months old) placed on January 31, 1921, in Chest 2 

 in pill boxes, 13 had emerged as moths by March 2, 16 emerged be- 

 tween March 2 and 17, 19 between March 17 and April 30, and 12 

 between April 30 and May 11 ; the remaining 40 died as larva? or 

 pupa?. 



Of 60 well-grown larva? placed in Chest 1 on January 31, 1921, 

 2 had transformed to the adult stage by March 2, 9 became adults 

 between March 2 and 17, and 14 between March 17 and May 11 ; the 

 remaining 35 died either as larva? or pupa?. Of 50 half to full-grown 

 larva? placed in Chest 3 on January 31, 13 emerged as adults by 

 March 2. Of the 2, 13, and 13 adults found emerged in Chests 1, 2, 

 and 3 on March 2, developing from larva? placed in chests on Janu- 

 ary 31, 1921, 2, 10, and 5, respectively, were alive, while 0, 3, and 8, 

 respectively, were dead. 



Half to full-grown larva? placed in Chest 2 on February 11, 1921, 

 developed into adults during the period March 17 to July 27; 1, 1, 

 8, 6, 4, 3, 7, and 1 being found during examinations made on March 

 17, 30, April 30, May 11, June 6, July 7, 15, and 27, respectively. The 

 adult found emerged during the July 27 examination, approximately 

 5^ months after the larva? were placed in the chest, was alive, very 

 active, and appeared no different in general vitality from others 

 emerging under normal laboratory conditions. One larva of this lot 

 was found alive, normal to all appearances, and very well grown, on 

 July 27, but had died by August 3. 



Half to full-grown larva? placed in Chest 1 on February 11, 1921 r 

 developed into adults during the period March 17 to July 23 ; 1, 8, 3, 



