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BOARD OF AGRICULTURE AND FORESTRY. 



Division of Entomology. 



PRI^XIPAL CITRUS INSECTS IN HAWAII. 

 By Jacob Kotinsky. 



(Continued from last "Forester.") 



NOXIOUS INSECTS. 



Primarily the citrus insects may be grouped as either injuri- 

 ous or beneficial. To those not familiar with correlating the 

 habits of insects with their appearance there are no ready ex- 

 ternal signs by means of which to differentiate the useful insects 

 from the injurious ones. It becomes necessary therefore to fami- 

 liarize ourselves with the appearance and habits of each species 

 separately in order to learn to distinguish friend from foe. As 

 the injurious insects require our first attention we will give them 

 first consideration. 



PURPLE SCALE {Lcpidosaplics piunccfoniiis, Bouche). 



No insect affecting citrus plants on these islands is more de- 

 structive to these plants. Checked but little by predaceous or 

 parasitic enemies, the scale, once it secures lodgment upon a tree^ 

 multiplies rapidly and continues sapping its vitality until the tree 

 is killed, unless some artificial remedy is applied. 



Larva. The group of scale insects to which the purple scale 

 belongs are rather peculiar in that through most of their lives 

 their resemblance to an ordinary insect is very slight or not at 

 all. When newly hatched the larvae bear six legs, a pair of 

 antennae in front, and two rather long waxy filaments projecting 

 behind, a pair of simple eyes and a short sucking beak. At this 

 stage no known difference between the sexes exists, and it is the 

 only period in the life of the female when she is not fixed to the 

 host. In this condition the insect remains but two or three days 

 in our climate, after which it attaches itself to the host, casts its 

 skin and begins to build the scale over itself — its permanent home. 



The female scale. — This consists mainly of waxy substance 

 which as it grows older becomes hardened, — leathery or horny. 

 In shape the scale is linear or mussel-shell-like, narrow in front 

 where it consists of the two skins cast by the insect in course of 

 growth and wider posteriorly. The first molt lies in front and 

 overlaps the second, which is larger and already covered with 

 considerable waxy matter. The scale proper then extends to 

 the rear so that the entire scale is about 2.5 mm. (o.i in.) long. 



