8 FUMIGATION OF APPLES FOR SAN JOSE SCALE. 



remembered that the young crawling San Jose scale is comparatively 

 fragile and quite susceptible to unfavorable conditions, and the 

 chances would be greatly against it even were the described condi- 

 tions present, very improbable in themselves. 



Danger of infestation in this way would be limited practically to 

 fruit on the market in late summer or early fall, as allowing a suffi- 

 cient time before cold weather for the insect to become about one- 

 third grown, since most individuals younger than this die during the 

 winter, as well as those much older. Ordinary winter varieties of 

 apples, as Ben Davis, York Imperial, Baldwin, Greening, etc., come 

 on the market in cool climates so late in the season as to practically 

 eliminate them as possible disseminators of scale under out-of-door 

 conditions. 



The history of the spread of the scale in the United States is of 

 interest in this connection. The insect was present in California for 

 years before its introduction into the East occurred. Much scale- 

 infested fruit was unquestionably sent to various eastern markets, 

 and thus unlimited opportunity was offered for its introduction in 

 this way. Its actual establishment, however, so far as known, was 

 brought about only by means of infested nursery stock received from 

 a locality in California where the insect was abundant. 



The foregoing remarks apply particularly to fruit consumed in the 

 fall or early winter. If the fruit is held for any time in cold storage, 

 the chances are still more increased against the insect's successful 

 establishment. Holding the fruit for any considerable time in cold 

 storage, in a temperature of from 30° to 32° F., results in the death 

 of the younger individuals and older ones, especially those in a 

 breeding condition. The survivors, as in the case of the insects under 

 winter conditions out of doors, are mostly those about one-third grown, 

 and the percentage of these which survive rapidly decreases with 

 continued holding in cold storage. Hence, after the insects are 

 again brought under favorable conditions, several weeks are required 

 for them to reach a reproductive age, and the fruit exposed to warm 

 temperatures for a necessary time for the development of the scales 

 would most certainly become badly deteriorated, if not actually 

 deeded, thus resulting in the premature death of the insects. In 

 practice, fresh fruit is perhaps never held so long in a warm tem- 

 perature before consumption. The probability of the young scales 

 being able to continue development to maturity on fruit parings, etc., 

 is scarcely to be considered, since this refuse would quickly decom- 

 pose or dry. 



The gradual dying of scales on fruit held in cold storage, during 

 1906-7 and 1907-8, is indicated in Tables II and XI, as determined 

 at different times for comparison with the condition of scales on 

 fumigated fruit. In the later examinations the live insects found 

 were exclusively those about one-third grown. 



