=i 5— 
sufficiently to prevent the temperature from going below freezing. 
Several examinations of infested stock plants kept in this manner 
demonstrated that most of the adult mealybuss and nymphs present 
are alive. However, from several collections of eggs, only a very 
small percentage have hatched, indicating the possibility that the 
eggs are susceptible to cool temperatures. To date, a few prelim- 
inary experiments have borne out the above conclusion. Further 
experiments with calcium cyanide fumivation indicate that the mealy- 
bug eggs are quite susceptible to it, increasing kills being ob- 
tained with dosages of from 1/8 to 1/2 ounce of calcium cyanide per 
1,000 cubic feet in overnight exposure. A hot-water treatment (110° F. 
for 15 minutes) was ineffective against all stages of mealybugs, in- 
cluding the eggs." 
Toxicity of sulphur to the broad mite.--F. F. Smith, of the 
greenhouse insects laboratory,.repurts: "In laboratory studies re- 
ported previously it was shown that sulphur was extremely toxic to 
Tarsonemus latus Bks., rapidly paralyzing and killing adults and larvae 
in 1 to 2 hours after dusting. The mites are not killed in the egg or 
advanced'pupal' stages but the emerging larvae or adults are killed 
by sulphur still present on the plants. These mites are killed even 
by volatilized sulphur taken up by air that has been passed through 
powdered sulphur and then filtered through cotton. The toxicity of 
sulphur vapors makes it unnecessary to dust all surfaces of leaves on 
greenhouse plants, as the mites on undusted parts are killed by sul- 
phur volatilizing from the dusted areas. In a greenhouse of heavily 
infested tobacco not a living broad mite was found, even on the lower 
undusted surface of large leaves, after a single application of pre- 
cip;itated sulphur dust. In recent tests for control on gerbera 100 
percent of 428 mites were killed by single dustings and infested plants 
in two greenhouses were freed of mites by the same treatment. Gerbera 
leaves are amony the most highly pubescent plants infested by this 
species ana the mites are accordingly afforded greater protection. 
Therefore the sulphur treatment received a very severe test for ef- 
fectiveness as control for the broad mite." 

Additional hosts of cyclamen and broad mites.--Doctor Smith 
further reports that "Since the preparation of the list of host plants 
for Tarsonemis pallidus Bks. and T. latus (published in U. S. Depart- 
ment of Agriculture Circular 301) the following additional hosts have 
been found: 
