you please help regards advice on bugs on hibiscus. Last year they
chewed at the flowers and I have been told be very careful what
you spray hibiscus with.
you have not described the bug that is eating your plant, I will
attempt to give you a general rundown of hibiscus pests, some of
which are worse than others. Caterpillars, for example, will eat
the leaves of the hibiscus plant, but their damage is mostly aesthetic.
Simply pick them off and destroy them.
Other pests include beetles,
which can also be picked off (except for the bronze beetle which
is a quick mover), snails and slugs, which like the new leaves of
mainly young hibiscus, and katydids and grasshoppers.
Katydids devour buds,
leaves and flowers, but they are not often seen because they are
nocturnal insects. During the day they hide out in long grass, so
remove any overgrown grass that may be growing nearby.
Stick insects, whilst
usually harmless to hibiscus, will lay their eggs on the plant.
The eggs drop to the ground and nymphs emerge in spring. The nymphs
will climb the hibiscus and eat the soft, new leaves. To deter this,
apply a ring of Vaseline around the base of the trunk. This will
also stop ants in their tracks.
Sucking and rasping insects
include aphids, scale, mealy bugs, thrips and spider mites. If you
are unsure which pest it is you have, click on the following link
to determine which bug is doing what.
If you have mealy bugs,
apply a mix of one part water to one part methylated spirits directly
onto the bugs using a paintbrush.
Thrips like dry conditions,
so frequent watering or misting will deter them.
Natural sprays for hibiscus
include pyrethrum, garlic and
onion sprays. All are short-lived, however, so regular spraying
Roughly chop 200 g garlic and soak in half a cup of mineral oil
for 24 hours. Mix 20 g of pure soap into a litre of water, add to
the garlic mixture and mix well. Strain, then use one part garlic
mixture to 10 parts water. This mixture can be stored in a cool,
dark place for several months.
Pour half a litre of boiling water over 1 kg roughly chopped onions,
strain, then use one part onion mixture to 20 parts water.
Some people swear by
Jeyes Fluid (a type of disinfectant) as a general insecticide. Mix
together 1 dessertspoon of Jeyes Fluid, 1 tsp dishwashing liquid,
1 tsp baking soda and 1 litre water.
Systemic chemical insecticides
such as Malathion or Maldison can cause defoliation, so milder,
non-toxic systemics, such as neem oil, are better.
Horticultural oil mixed
with water may be your best spray, but do not apply when the sun
is at its hottest or you could damage the leaves. Similar to horticultural
oil is insecticide soap, which is also good.
by Dr Dan Blanchon from Unitec's Diploma in Sustainable Horticulture and Bachelor
of Resource Management.
with permission from NZOOM Home and Garden content,
from the previous
The views expressed here are not necessarily those of the RNZIH