6 MASS. EXPERIMENT STATION BULLETIN 326 



ACTION OF NAPHTHALENE FUMES 

 On Insects and Spiders in General 



Reports by Speyer (16) and Hartzell (6) show that naphthalene has a 

 selective toxicity to the common red spider and the greenhouse thrips (p. 19 

 footnote^, and as a fumigant gives better control of red spider with safety to 

 many plants than other known fumigants. Therefore, the experimental studies 

 and the practical development of naphthalene fumigation have been based 

 largely on its effectiveness as a control for the common red spider. 



The toxicity of naphthalene to insects and spiders is apparently dependent 

 upon a relatively long exposure in air containing naphthalene vapor. The 

 action of these fumes on the insect is paralytic and the first evidence is shown 

 by a lack of control of the legs and other appendages even though they can 

 be moved freely. The cause of this action is not definitely known, although 

 it appears that the gradual paralysis is due to the partial exclusion of oxygen 

 from the respiratory system. With continued exposure paralysis increases 

 until death results, and there is no evidence that the body tissues are burned 

 or seared in any way. Four or five days after death the bodies of the fumigated 

 insects and spiders collapse and dry. 



The high temperature and high relative humidity which are necessary for 

 successful naphthalene fumigation provide conditions tending to increase res- 

 piration and body metabolism in animals, thus aiding the penetration and 

 toxic action of the naphthalene fumes. It is also apparent that naphthalene 

 fumes penetrate the chorion of the egg and kill the embryo in the same way 

 that the active stages are killed. 



Early in the studies it was observed that the different stages of the red 

 spider possessed a varying degree of resistance to fumigation, and experiments 

 were therefore conducted with eggs, larvae, nymphs, and adults. 



On Red Spider Eggs 



In 1927, Read (12) reported that eggs were killed by an eight-hour exposure 

 to a saturated atmosphere of naphthalene at 100° F., and that the time re- 

 quired to kill them decreased as the temperature and atmospheric moisture 

 increased. However, this temperature is higher than can be maintained under 

 practical conditions. 



At Waltham newly laid eggs failed to hatch after two or more fumigations 

 of six hours duration using 3 ounces of naphthalene per 1,000 cubic feet at 

 75° F., as shown in Table 1. 



Table 1. — Mortality of Red Spider Eggs on Carnation Leaves after 

 Fumigation with Naphthalene. 



Temperature 75°F. Relative Humidity 80 — 90 percent. Exposure 6 hours. 

 Dosage 3 ounces per 1000 cubic feet. 

 Waltham, Massachusetts. April 1930. 



Number of Number of Percent 



Fumigations Eggs Hatched 



None 46 89.13 



1 48 12/50 



2 43 



3 46 



4 48 



