128 INSECTS AFFECTING VEGETATION 



mite. In order to kill the eggs and moulting forms it will be neces- 

 sary to make three applications, separated by intervals of one week. 

 This will make a very clean sweep. (Bui. 145, Cal. Agr. Exp. Sta.) 



The Scale Insects of the Date Palm. To the naked eye the 

 scales appear as small dark-grey or black specks, edged with white, 

 At one end will be seen a small oval object, which is the first skin ; 

 that is, the skin shed by the young at its first moult. The large 

 shield-shaped object is the second skin, and the white surrounding 

 part is the scale secreted by the insect in its last stage. The date 

 scale when once established, spreads rapidly, damages the foliage of 

 the date palm and renders the fruit unmarketable, being therefore 

 a serious menace to the industrial future of the tree under our 

 climatic and cultural conditions. Fortunately, however, the limited 

 size of the broods, insect enemies, the probably wingless condition 

 of the male, and the fact that this scale so far as now known has no 

 other food plants in this region, all tend to limit the numbers and 

 range of the insect; For remedies see under heading of the Marlatt 

 Scale. 



The female insect is from 1 to l 1 /^ mm. long, and secretes a 

 white waxy substance but does not produce any true scale like that 

 of the Parlatoria. 



The Marlatt Scale, because of its closer confinement to the bole 

 of the palm, is comparatively harmless and to be regarded with less 

 apprehension. 



To free the palm trees of these two scales, first cut back close to 

 the bole all old leaves that are badly infested and then thoroughly 

 go over the trunks and leaves with the flame from a gasoline torch. 



With the radical and thorough method of treatment by burn- 

 ing at command, described above at the same time fatal to scale 

 insects and not seriously injurious to the palms, and with a suitable 

 law for the application of the method, there is no reason, except lack 

 of vigilance, why the scale insects affecting date palms may not now 

 be considered under control in Arizona. (Bui. 56 Ariz. Exp. Sta.) 



The Pineapple Scale. This pest of the pineapple is a scale in- 

 sect, one of the Coccidse, which, because of its special fondness for 

 this plant, has received the common name the "Pineapple Scale." 



These small, scale-like insects are very conspicuous, because of 

 their color, and not easily mistaken for other forms. The scale and 

 not the insect itself is the object commonly seen. The insect is 

 found beneath this secretion, which serves as a shield. In the case 

 of this insect the scale or protective armor is made up partly of a 

 waxy secretion of the insect and partly of molted skins. The insect 

 itself in the adult stage is quite well buried beneath the epidermis 

 of the plant and hence the necessity of combating the pest in its 

 early stages. 



The pineapple scale can be controlled by spraying where it 

 occurs in the field with kerosene emulsion or the resin wash, 1 part 

 to 10 of water. The cheaper and easier method is by proper preven- 

 tive measures to keep the pest from gaining a foothold in the planta- 

 tion. These measures are to burn all leaves where the pest is at all 



