50 COLLECTING AND PRESERVING COCCID^E. 



from the natural products of these insects. Such ex- 

 hibits are highly educational, and so also are the life- 

 histories of the injurious species. 



As to the mimetic species, I may mention the extra- 

 ordinary Physokermes abietix, Geoffrey. The female 

 of this species locates itself behind the old bud-scales 

 of the spruce fir, and so exactly resembles the un- 

 opened bud of the tree that it is difficult at first to 

 detect it. 



Mould is the greatest enemy to the specimens, 

 especially to those having delicate waxen coverings or 

 ovisacs, which when once infested are utterly useless 

 as museum specimens, as they can never be restored. 

 The best preventive against mould is the free use of 

 carbolic acid in the cabinet drawers or boxes, as the 

 case may be. Mould is generally set up by an excess 

 of moisture. In my own collections this has been un- 

 doubtedly due to the gum used for mounting the speci- 

 mens, or from portions of the food-plant which had 

 not been thoroughly dried before placing them in the 

 cabinet. By adding a few drops of carbolic acid to 

 the gum, and by thoroughly drying the specimens, 

 mould may be prevented, providing always the speci- 

 mens are housed in a dry place. " Mites " (Psocidse) 

 simply revel among stored specimens of the Coccida?, 

 but the free use of naphthaline of the form known MS 

 albo-carbon is a perfect preventive. 



METHODS OF PREVENTION AND REMEDIES. 



As Coccids subsist upon the sap or juice of the plant 

 which they attack, by sucking it up with their rostrum 

 from the interior of the leaf or twig, it is obvious that 

 any application made for their destruction must neces- 

 sarily be such as will kill them by affecting the respi- 

 ratory organs, such as hydrocyanic gas ; or by direct 

 contact with their bodies, such as washes and emul- 

 sions. Paris green, or any such mineral poison which 



