Snow scale, banana & citrus Minimize
   

April 2010. The two scales were recorded as snow scale (Unaspis citri), but are they the same?  One came from citrus (photo, right), the second banana (photo, left).

Later, a member replied: 

It is not really possible to see adult female scale covers clearly so it is difficult to say anything authoritatively. However, the male scale covers on citrus are clearly ridged whereas those on banana are not. Probably, they are two different genera.

The banana scale has non-ridged immature males and could be a species of Diaspis (the relatively circular exuviae on the adult female scale would support this) (photo, second row left). On Scalenet there are records of Diaspis boisduvalii Signoret being found on Musa – see:

http://www.sel.barc.usda.gov/scalecgi/scaleson.exe?family=Musaceae&scalefamily=Diaspididae&genus=Musa&scalegenus=Diaspis&species=

According to Beardsley (1966), Palau has D. boisduvalii. This species is recognizable because the adult female usually has a fleshy lateral projection on either side of the cephalothorax and a notch in the rear end – see the attached picture.

The citrus scale has ridged immature males, so the images could be a species of Pinnaspis (photo, second row, right) or Unaspis (photo, third row, left) or something related to them. Beardsley (1966) reported P aspidistrae (female scale cover flimsy and brown) and P. strachani (female scale cover flimsy and white) in Palau, but not U. citri (female scale cover more robust, rippled and dark purple-brown). U. citri can be a very serious pest on citrus.

Original: 
http://tech.groups.yahoo.com/group/pestnet/message/7022