Report of the State Entomologist. 



187 



Spread of Scale Insects. 



In illustration of the evils often attendant upon a change of food-plants and exten- 

 tion of range, and also the increased destructiveness of introduced species, we may 

 refer to the struggle which the fruit growers of California are at the present time 

 undergoing with insect pests, and notably with scale-insects, which liave followed the 

 recent extended culture of the citrus fruits, particularly the orange, in that State. 



Attack by the members of this family, known as the 

 Coccida', is always dreaded, as they multiply with amaz- 

 ing rapidity, and are protected during nearly all of their 

 life by a shield-like covering which is impervious to 

 such applications as ordinarily suffice to destroy more 

 exposed forms. They are not even amenable to the 

 poison of arsenical preparations, which are our best 

 insecticides wherever they may be safely employed, as 

 they find their food in the juices of plants, extracted 

 by means of a needle-like proboscis driven through the 

 bark, or epidermis of the leaf. 



The scale-insect, which is especially enlisting wide- 

 spread attention in California, receiving the most care- 

 ful study, and, from the difficulty of its control, exciting 

 great alarm, is known as "the fluted scale," or "the 

 cottony-cushion scale," from the peculiar and conspicu- 

 ous cotton-like mass attached to it and sheltering its 

 eggs. Scientillcally it is known as Icerya Purcltasi 

 Maskell. Australia, South Africa, New Zealand and 

 California are its only localities, so far as known to us. 

 Its original food-plant is believed to have been an 

 Acacia — thorny trees or shrubs belonging to the Leyu- 

 minosd', of which we have no native species north of 

 Texas. On an Acacia imported. from Australia it was 

 in all probaltility introduced into California in 1808 or 

 1860. From this plant it spread to various orchard and 

 ornamental trees, garden plants, weeds, etc. A few of 

 these may be enumerated as showing the possible 

 range of some of these pernicious scales: Orange, 

 lemon, quince, pomegranate, apple, pear, peach, apri- 

 cot, flg, strawberry, grape, hawthorn, walnut, oak, 

 pine, cypress, laurel, locust, elm, willow, ivy, rose, ver- 

 bena, and box. According to a writer in New Zealand, 

 " it attacks all sorts of plants." It is proving particu- 

 larly destructive to the orange, entire plantations of 

 which have been completely destroyed. Not yet over- 

 spreading the entire State, the most earnest efforts are 

 being made to arrest its distribution. Laws have been 

 enacted, under which fruit inspectors have been 

 appointed, whose duty it is to enforce the laws, and 

 even to search out the infested trees and compel their 

 destruction. 



The interest taken in this crusade against insect 

 pests in California, and the desire to conduct it in the 

 most efficient manner, is shown in the following extract 

 from an address recently made by the Secretary of the 

 California Horticultural Society: 



"Every effort is being made by horticulturists to 

 resist the spread of fruit-pests. Every method sug- 

 gested by reliable scientists and fruituK^ is being 

 thoroughly tested. Usually not much urging is 

 reauired to in<luce the owners of pest-ridden orchards 

 to try the latest discoveries, as they are only too willing 

 to attempt the eradication of their insect enemies. In 

 this way many new applications are being discovered. 

 If we can succeed in checking the ravages of the pests, 

 this State is bound to become the orchard of the 

 world," (Pacific Bural Press, August 20, 1887, p. U5.) 



Fig. 68.— The cottony cushion- 

 scale, ICEETA PUBCHASI, OXX 

 orange, 



