62 HYDROCYANIC-ACID GAS FUMIGATION IN CALIFORNIA. 
required without injury to the fruit, although probably it would be 
preferable to fumigate a little later in the fall. The purple scale can 
be found in the egg stage throughout the year. There is, however, 
a period in the fall during which the smallest proportion of eggs is 
to be found. With dosages lower than that of eradication the best 
results can be accomplished at this time, which usually is somewhere 
about October. The red and yellow scales are born alive and can 
be successfully destroyed throughout the year. 
In fumigating for any of the scale insects there is one point worthy 
of consideration. Aside from trying to save the tree from destruc- 
tion or from having its vitality impaired by the attack of scale pests, 
the orchardist fumigates principally in order to have his fruit come 
into the packing house as clean as possible. It would be well, there- 
fore, to fumigate as nearly as possible at the time which would insure 
him the cleanest fruit. Although lemons are gathered throughout 
the entire year, the bulk of the orange crop is taken during the first 
six months. Thus fumigation during the fall and early winter 
would be sure to place the cleanest fruit in the packing house. If 
carried on in the late spring or early summer, such insects as remain 
undestroyed would have the opportunity to breed throughout a period 
of several months and infest much fruit. 
The small size of the fruit and to some extent the heat renders 
fumigation generally unsafe before the month of August. From 
this time up to December the weather is usually quite dry and not 
especially cold. December is usually the month during which cold, 
rainy, and generally unsettled w T eather may be expected to com- 
mence and to continue with more or less irregularity into the follow- 
ing March. Serious injury to the trees may result unless the greatest 
care is exercised in treating during these winter months. At this 
period most fruit is almost fully grown, which adds a great weight 
to the tree. Covering heavily laden trees with fumigation tents not 
only tears off and scars a considerable amount of fruit, but also 
breaks off heavy branches. The writer does not believe it advisable 
to treat trees in such condition. 
The labor question, at all times a perplexing one in fumigation 
operations, is especially serious where the work is carried on in the 
winter. The frequent delays, possibly for several days at a time, 
necessitated by the rainy and damp weather render it difficult to 
secure good and careful men who will remain continuously with the 
outfits. As they are paid only for actual work performed, operators 
earn little more than their living expenses during the irregular hours 
when work is possible in the winter season. 
After viewing all sides of the question, it is advised that the prefer- 
able months for general fumigation are from August to December. 
The treatment can, however, be carried on with both safety and 
