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VII. 
SOME HERTFORDSHIRE SCALE-INSECTS. 
By John Hopkinson, F.L.S., F.G.S., F.E.M.S., etc. 
Read at Watford , 21 st April, 1903. 
There are frequently to be seen on oranges, and occasionally 
on lemons, little light or dark brown or black spots, circular or 
oval in outline and flatly conical in form. If a fruiterer be asked 
what they are he will probably say that they are seeds which have 
accidentally stuck to the fruit. They are not, however, of vegetable 
origin at all, nor is there anything accidental in their attachment. 
They are minute insects which are living upon the juices of the 
fruit; they are, in fact, coccids or scale-insects, the Coccidse 
forming a family of the Hemiptera-Homoptera, which include the 
Aphididse, Cicadidse, and some other less-known families, and, with 
the Hemiptera-Heteroptera, constitute an order (Bhynchota) of the 
haustellate Insecta. The scale-insects which are commonly seen 
on the rind of the orange belong to two species of the genus 
Parlatoria (P. pergandii and P. zizgphi), the latter being most 
frequent on the Tangerine and Seville varieties, but species of 
other genera (Aspidiotus and Mytilaspis ) also occur. 
The insects of the order Bhynchota have suctorial mouths, and 
these the coccids fix upon their food-plant where the sap flows 
most freely. It is, however, only the female coccid which has 
a mouth, and she is wingless; for the absence of a mouth in the 
male coccid he is compensated, usually, by the possession of two 
wings, which he so little values that he has not been observed to 
use them voluntarily; and throughout their very peculiar meta¬ 
morphoses, the males, when the larval stage is passed, differ 
greatly from the females. The eggs are always protected, the 
shield-like scale which covers those of some species having given 
to them their popular name of “scales,” and the loose cottony 
material of others being responsible for the popular term applied to 
them of “mealy bugs.” The female lays eggs only once in her 
lifetime, but that is often enough for their rapid propagation, 
a single brood varying in number from about 20 to upwards of 
2,000. It will thus be seen that the life-history of the coccids is 
peculiar and of great interest, the metamorphism which they 
undergo being different from that of any other insects. 
I have mentioned the occurrence of the scale-insects upon the 
orange and lemon as an example familiar to everyone, but they also 
occur on other fruit, and on the stems and leaves of plants, from 
the delicate maidenhair fern to the sturdy forest oak, and as they 
live upon the juices of the plant they are in all cases detrimental, 
and frequently they are injurious to the extent of killing the 
plant which they attack. 
VOL. XII.—PART II. 
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