you tell me what is wrong with my house plant? It has had this leaf
condition for quite some time with no signs of improving.
alocasia leaf you sent is infested with thrips, tiny insects that
feed by rasping away at cells on the undersides of the leaves and
sucking out their juices. The dead cells create silvery patches
on the leaves which can eventually turn brown, and badly infested
leaves may drop off.
Adult thrips are tiny
blackish looking insects, just visible with the naked eye, while
young thrips are smaller and semi-transparent sometimes with a blackish
head and dark markings on the body. Often easier to spot are the
sticky, shiny black blobs of droppings scattered around on the undersides
of the leaves where they've been feeding. Thrips are common pests
on a wide range of outdoor plants and adults can fly or be blown
indoors on a breeze. With indoor plants you can reduce their numbers
by picking off badly infected leaves. If you only have one or two
plants to treat you could take them outside and spray with one of
the aerosol insecticides such as Baythroid or Confidor, according
to the label recommendations. Regular washing and wiping of leaves
on indoor plants is also a good way of reducing thrips damage. And
for the record, the name is always spelt thrips - there's no such
thing as one thrip, only one thrips!
Gardener, Issue 175, 2005, Page 30
Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.