18 HONEYDEW. 



furnish an excellent dye, which in former times was of 

 much value also."* 



HONEYDEW. 



The honeydew secreted by Coccids is a clear gluti- 

 nous substance, appearing on the leaves of plants as a 

 thin coat of transparent varnish. No analysis of it 

 has been given, but from its attractive qualities to 

 insects it is undoubtedly analogous to that produced 

 by the Aphids. It is rarely found to accompany tli<> 

 shield-bearing Uicixpiiiae, but the amount secreted by 

 large colonies of various "brown scales" (Lecanium, 

 spp.) and " mealy bugs " (Dadtjlopius, spp.) is some- 

 times enormous. 



In the Lecaiiia the greatest amount of secretion 

 takes place immediately prior to and during the period 

 of parturition, and with the indigenous species it 

 occurs chiefly in May and the early part of June ; but 

 with those species attacking plants under glass it 

 occurs indefinitely, and is generally present where 

 large colonies of Coccids are allowed to remain unmo- 

 lested. The females only have the power of secreting 

 the honeydew, which passes out through the anal 

 opening, and may therefore be considered as the na- 

 tural excreta of these insects. In his account of New 

 Zealand "scale insects" (1887), p. 16, the late Mr. 

 Mask ell mentions a special organ for the secretion of 

 this substance as a " cylindrical tube exserted from 

 the ano-genital orifice after the manner of a telescope, 

 the furthest extended tube being the most slender. 

 This organ, extremely difficult of detection when not 

 in use, except in the single genus Ccelostoma, Mask., is 

 at intervals pushed out to its full extent, and at its 

 further extremity there appears a minute globule of 

 yellowish, nearly transparent glutinous fluid, which 



* Newstead. " Injurious Scale Insects and Mealy' Bugs of the British 

 Isles/' ' Royal Hoi-t. Soc. Journal,' vol. xxiii, pt. 3, 1900. 



