176 



AMERICAN HOMES AND GARDENS 



September, 1906 



A New Apple-Tree Pest in California 



By Enos Brown 



jHE Parajo Valley, which embraces portions 

 of Santa Cruz and Monterey Counties, 

 constitutes the greatest apple-growing 

 district in all that part of the country lying 

 west of the Rocky Mountains. Its con- 

 tiguity to the ocean and the richness and 

 fertility of the soil render the conditions ideal for apple 

 culture. The fruit grows to such astonishing size and at- 

 tains such surpassing flavor that it is largely exported. In 

 all there are 1,000,000 trees growing on 812,000 acres of 

 land and 100,000,000 pounds of the fruit are shipped every 

 year. The culture of the apple has been extremely profit- 

 able. The orchardists reaped large returns until the intro- 

 duction of the codlin moth from the east, when the orchards 

 became badly infected with the devastating insect. The 

 attempts of growers to extirpate the pest proved futile and 

 the aid of the general government and the University of 

 California was solicited and obtained. 



The life history of the moth under California environ- 

 ments was carefully investigated by the scientists and its 

 habits studied with such success that full control of the pest 

 was effectually gained and its ravages controlled. The sea- 

 son for spraying, or the exact moment when the application 

 of arsenical solutions was most destructive to the moth and 

 its progeny, was ascertained and other methods of preven- 

 tion discovered, so that with reasonable care and industry 

 on the part of the orchardists the dreaded enemy of the 

 apple was divested of its power to harm and its destructive- 

 ness almost entirely curbed. The loss to the orchard was 

 reduced from sixty-seven per cent, to less than five. 



No sooner, however, had the codlin moth been disposed 

 of than another pest made its appearance upon which 



arsenical solutions had no effect and which was more destruc- 

 tive than the codlin moth. 



In 1903 the new moth began to be noticed and was recog- 

 nized as the identical one which devastated the orchards as 

 far back as 1887, sixteen years before, when it appeared for 

 one season only and then vanished after leaving unmistak- 

 able traces of its capacity to harm. The reason for its early 

 disappearance after its first visit could not be explained but 

 is believed to have been due to the attack of a natural enemy 

 which the entomologists hope to rediscover. 



Scientists have named the new caterpillar the "Hinero- 

 campa-vestuta," though the local name is the "Tussock" 

 moth. Popularly it is called the "California caterpillar." 

 It is said to be not of record in current scientific publi- 

 cations. The new and formidable apple pest is said by 

 entomologists to be a native of California. 



The "tussock" moth as studied at the laboratory at Wat- 

 sonville, by Professor Volk, of the University of California, 

 is described as appearing in limited numbers in the Pajaro 

 District in 1903, when it first attracted attention. A year 

 later its numbers were prodigiously increased and the 

 strongest arsenical sprays were powerless to arrest its ravages 

 The tussock moth deposits its egg, in May or June, in masses 

 a quarter of an inch in diameter, each containing 200 to 250 

 each, surrounded by the usual web. These balls are de- 

 posited all over the tree on twig and branch and the eggs 

 are hatched in the succeeding February or March. The 

 only effective method found for reducing the numbers of 

 the pest is to hand-pick the egg balls off the tree, and so vast 

 are the numbers that from the trees of one orchard covering 

 sixty acres, one hundred boxes, each holding a bushel were 

 taken. This almost incredible story is vouched for by Pro- 



Tussock Larvae Collecting Under a Tangle- 

 foot Band. A Useless Device 



Muslin Bag Breeding-Cage 



Laboratory-Cage for Studying Life History 

 and Habits of the Tussock Caterpillar 



