GARDEN PESTS IX NEW Z E A L A X D 



in all the coccids, are usually minute, and, with few exceptions, two- 

 winged (Fig. 5) ; none has mouth parts, these appendages having become 

 atrophied during metamorphosis, which is complete, while many have 

 one or more hair-like tail appendages. On the other hand, females are 

 never winged ; some are comparatively large ; all have well-developed 

 mouth parts throughout life, and undergo incomplete metamorphosis, 

 while in many forms the legs and antennae are lost before maturity. 



In all cases coccids secrete a protective covering, which assumes 

 different forms; this fact, together with the chief methods of female 

 development, is utilised for the purpose of this work to arrange the 

 coccids under three main types as follows : 



1. LESS SPECIALISED FORMS. Examples are the mealy-bugs and 

 cottony-cushion scale, which belong to the more generalised or least 

 specialised representatives. The protective body covering is in the form 

 of a powdery or mealy secretion; the legs 1 and antennae are retained 

 throughout life, and the insect remains freely mobile. 



A typical-form life-cycle may be studied in that of the cottony- 

 cushion scale (Figs. 5 and 6a). During development the female insect 

 passes through three larval stages; each of these stages is, on the whole, 

 similar, except for size and minor structural changes, and the white 

 powdery secretion that covers the reddish body of the adult. 



2. INTERMEDIATE FORMS. An example is the olive scale (Fig. 5). 

 In such forms there is a tendency to specialisation, owing to more or 

 less sedentary habits in later life, and protection is afforded by a thicken- 

 ing and toughening of the cuticle on the upper surface of the body 

 Unlike the cottony-cushion scale, the female olive scale passes through 

 two larval stages ; the minute first stage larva is active and very flat ; it 

 soon settles upon a leaf and commences to feed, when it becomes much 

 flatter and a little larger; the second stage differs from the first in size 

 and in the development of a dorsal longitudinal ridge, which eventually 

 forms the cross-bar of the two transverse ridges that are characteristic 

 of the third or adult stage, when the insect swells and assumes the shape 

 of the mature form. After settling in the first larval stage, the insect 

 becomes very sluggish, and does not move, except to migrate, as most 

 do, from the leaves to the twigs, there to take up a permanent position. 

 The legs and antennae are retained throughout life, but in the adult are 

 functionless, being folded against the body; in some species of inter- 

 mediate forms the appendages become atrophied during development. 

 In the olive scale, and related forms, the toughened cuticle not only 

 serves as a protection to the insect, but also as a receptacle for the eggs 

 (Fig. 5) ; as these are laid and increase in numbers, the* body of the 

 parent diminishes and is crowded against the dome-shaped cuticle. 



3. SPECIALISED FORMS. The apple mussel-scale (Figs. 5 and 7, 

 Nos. 2 and 6) is a representative of this group, the members of which 

 are markedly specialised, the legs and antennae of the adult female 

 becoming completely atrophied during development, and the shape of 

 the body profoundly altered; protection is afforded by a scale-like 

 covering not attached to the body. In the mussel-scale development 

 there are two larval stages: the first, like all coccids, has the legs and 

 antennae well developed and is active. 



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