EXPERIMENTS AGAINST CLOTHES MOTHS. 23 



moths were killed in from three to four days when confined in these 

 boxes. From 18 to 25 days were required to kill 85 to 90 per cent of 

 the half -grown larvae when placed in the boxes. 



PAEADICHLOEOBENZENE. 



Effect on clothes-moth adults and larva?. — Paradichlorobenzene 

 killed only 30 per cent of the adult moths and none of the larvae 

 placed in a room of 846 cubic feet capacity. Eight and one-half 

 pounds of paradichlorobenzene was exposed in 6 dishes for 21 hours, 

 and during this time one-half pound of the material evaporated. A 

 liberal amount of paradichlorobenzene scattered on infested flannel 

 in an open jar killed all of the exposed larvae in 20 hours. 



In boxes, trunks, or closets this substance would, no doubt, be very 

 effective, when used liberally, as indicated by its rapid killing effect 

 against clothes-moth larvae when confined in a small space ; but owing 

 to rapid evaporation its effectiveness would not last nearly as long- 

 as that of naphthalene. 



PYEETHEUM POWDEB. 



Effect on clothes-moth larvae and eggs. — Pyrethrum powder was 

 found to kill 100 per cent of larvae on infested flannel, even when 

 used in proportions as low as 4 parts of pyrethrum powder to 96 

 parts of flour. 



Two tests were made with pyrethrum powder against clothes-moth 

 eggs. Whether or not the eggs were prevented from hatching has not 

 been determined definitely. If any hatched, however, the resulting 

 larvae died immediately, since 16 days after treatment no larvae were 

 found and the flannel was not damaged. 



While no test with pyrethrum powder was made against adult 

 clothes moths, it is safe to say that the powder would kill the adults. 

 Clothing thoroughly dusted with pyrethrum powder would be pro- 

 tected from larvae resulting from any eggs that might be present. 



HYDBOCAEBON OIES AND OIL EMULSIONS. 



Effect on clothes-moth adults. — Various oils of the nature of 

 kerosene have proved very effective in preventing infestation of 

 larvae, resulting from moths liberated in cages, as described on pages 

 16 and IT. However, flannels treated with oil emulsions at dilutions 

 varying from 1 part of emulsion in 65 parts of water to 1 part of 

 emulsion in 250 parts of water were not protected from infestation. 

 It is necessary to use such emulsions either undiluted or only 

 slightly diluted if satisfactory control is to be expected. 



The vapors evolved from kerosene in a closed jar killed adult 

 moths in 2J hours, the experiment being so arranged that the moths 

 were not in contact with the oil. 



