Although their color can vary
through the year, actively feeding two-spotted spider mites are
usually greenish-yellow, with a dark spot on either side of the
abdomen. Those spots are actually an accumulation of bodily wastes
and may not be visible on immature life stages. They are generally
found on the undersides of affected fronds. You might even be able
to see fine webs covering severely infested areas of the palm.
Spider Mites Life Cycle
Their development is accelerated
by a warm, dry environment. Under optimum conditions, the time from
egg to adult can take as little as five days. Adult females can live
for two to four weeks, and may lay several hundred eggs over her
lifetime. There are many overlapping generations through the year,
especially under indoor conditions. Two-spotted spider mites are
common pests of outdoor trees, shrubs and flowering plants during
hot, dry summer weather. Of course, indoor heating systems create
warm, dry conditions through the winter that can create the same
conditions for our houseplants, especially those that may acquire
these pests from spending summer months outdoors.
Two-spotted spider mites feed
with piercing-sucking mouthparts, which means that they insert their
mouthparts into the frond much like a very small hypodermic needle.
As they feed, they literally suck the chlorophyll out of the leaf,
which is why the fronds have such a bleached out appearance.
Spider Mite Control Measures
Since two-spotted spider mites
are arachnids, not true insects, regular insecticides do not control
them very well, and often create an outbreak by killing natural
predators (outdoors) and perhaps making host plants more nutritious
for these pests, depending on the insecticide applied to them.
Their rapid reproduction rate
can make two-spotted spider mites difficult to control – large
populations can build up before you realize it. Repeated
applications of ultra-fine horticultural oil will get them under
control. Although insecticidal soap is also labeled to control spider
mites, many palms are so sensitive to insecticidal soap that the
damage from the soap application is worse than the damage from the
The bleached out appearance of
damaged fronds will not go away until those fronds are replaced with
new ones. You can prune out the fronds with the worst damage, or
those that show webbing, to reduce the overall mite population
before you start making horticultural oil applications.
Be sure to purchase ultra-fine
horticultural oil, or summer-weight horticultural oil, rather than
dormant oil. Horticultural oil is lighter and more refined than
dormant oil, and less likely to burn tender plant tissues.
Flower Pots need good drainage