SOME SCALE INSECT PESTS OF 

 COFFEE IN SOUTH INDIA. 



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Introduction. 



The Scale lusects or Coccidfe form a large group embrac- 

 ing some of the most serious pests of cultivated plants and 

 at the same time including useful forms such as the cochi- 

 neal and the lac insects. Text-Fig. 1 shows the external 

 structure of one of these insects and may be taken to re- 

 present the group in general. The popular name, scale 

 insects, appropriatel}^ describes their scab or scale-like 

 appearance. The shape is usually flat and oval but is 

 often obscured by secretions of a resinous or waxy nature 

 and by ovisacs or egg bags at the hind end of the body. 

 There is usually little or no trace of segmentation, the 

 three natural divisions of the body, viz., the head, the 

 thorax and abdomen running into one another. There are 

 three pairs of legs ending in hooks. The eyes are minute 

 black spots near the margin. The mouth is situated be- 

 tween the first pair of legs. The mouth parts consist of 

 four long slender hairs closely approxunated to form a tube, 

 along which the plant sap is drawn. When not in use, 

 this tube is withdrawn into a special sac inside the body 

 where it remains in the form of a loop, the sharp point 

 only appearing outside. For the manipulation of the pro- 

 boscis there are a number of muscles which converge into 

 a small chitinous cradle (see Plate II, Fig. 3). 



The sexes of scale insects are sharply differentiated in 

 the adult stage. The females retain more or less the flat 

 oval shape and are wingless. The males, on the other hand, 

 are provided with a pair of wings and a pair of eyes, but 

 have no feeding apparatus. The reproductive powers of 

 scale insects are -enormous. The number of young pro- 

 duced may reach several hundreds and a large number of 

 species reproduce without the assistance of a male. The 



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 INSTITUTION AUb 1 1 l9w 



