INJURIOUS INSECTS OF 1904. 



29 



Can the Moth get through ivire mosquito netting? Moths confined for several 

 days in a cage made of wire netting, 144 meshes to the square inch, did not 

 escape, dying within the cage. 



Eifcct of liquid Carbon Bisulphide on eggs, larvce, pupce and moths: One con- 

 tact for a few seconds with this liquid killed eggs, young and full-grown larvae 

 and moths. The pupae were not killed immediately, but died later. 



Least volume of Carbon Bisulphide (CSi) and least time of exposure necessary 

 to kill full-grown larvce and moths by fumigation: 



Condition of Insect. 



Full-grown larvae. 



Full-grown larvae.. 



Full-grown larvae 

 and moth 



Full-grown larvae 

 and moth 



Strength of Gas. 



I Part liquid CS2 to 1,500 parts 

 atmosphere 



I Part CS, to 3,000 parts atmos- 

 phere 



I Part CS2 to 6,000 parts atmos- 

 phere 



I Part CS2 to 12,000 parts atmos 

 phere 



Time Exposed 



I hr. 40 min. 



1 hr. 



2 hrs. 



3 hrs. 



Results. 



Killed. 

 Killed. 

 Killed, 

 Killed. 



Effect of exposure of moths, eggs, larvce and pupce to knoivn lozv temperatures 

 for definite lengths of time: 



Lot No. I. Exposed out of doors in breeding jar, for three days, to a temper- 

 ature ranging from 18 degrees above to 12 degrees below zero. 

 All killed. 



Lot No. 2. Placed in cold storage at 32 degrees for four days. Living at expi- 

 ration of that time. 



Lot No. 3. Placed in cold storage at 14 degrees above zero for four days. A 

 few worms survived. 



Lot No. 4. Placed in cold storage at 6 degrees for four days. "Worms" sur- 

 vived. 



Lot No. 5. Placed in cold storage at i degree above zero for four days. All 

 killed. 



Lot No. 6. Placed out of doors for four days, temperature ranging from 18 

 above to 21 below zero. One or two worms survived. 



It would seem, then, from the above, and from the experience of millers 

 cited on page 28, that the "freezing process" to be thoroughly effective must 

 be most thorough. Mills should be so constructed that all water pipes can be 

 emptied, allowing all parts of the mill to get extremely cold. Further, since we 

 know that a long continued even cold temperature is not always fatal to insects 

 (note the hibernation of Minnesota insects, for example), but that exposure 

 to cold and thawing alternately is fatal, we would suggest that millers in this 



