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Spider mite
What is a spider mite?
A spider mite is a plant-eating, web-spinning mite (family Tetranychidae)
that resembles a tiny spider and is frequently a serious garden and
greenhouse pest. Two-spotted spider mites (Fig. 1) are 0.25 to 0.5 mm
long, eight-legged, with two large spots on both sides of the body. The
spider mite life cycle goes through five stages, namely egg, larva, first
nymphal stage, second nymphal stage, and adult. All stages can be
observed in the crop.
fact sheet
Damage.
Figure 1. Two-spotted
spider mite
Spider mite larvae, nymphs and adults feed on the underside of leaves
and cause yellow spots, later even yellow leaves; damaged leaves can
drop from the plant. This results in decreased plant growth and
production. Finally the crop may die from large infestations.
Nymphs and adults produce webbing that can cause cosmetic damage
to the crop. If large numbers of spider mites are present, plants may be
completely covered with webs.
Detection.
For detection of spider mites, use a magnifying glass or hand lens.
Examine the undersides of the leaves closely for adult mites and
webbing; underside of leaves will start to yellow.
Figure 2. Yellow spots on
leaves from spider mite
damage
Use a sheet of white typing paper beneath the leaves and strike the
foliage sharply. The mites will fall onto the paper and can be more
easily observed and identified than on the green foliage.
Control.
Make sure mite screen on hoop house is in place in order to minimize
mite outbreaks. For low populations of less the 10 mites per leaf, rinse
the leaves of the plant; more than ten mites per leaf, start spray
program or use biological control.
Figure 3. Spider mite
webbing
Webbing indicates that high populations are present and use of a spray
program is the only effective means of control.
Figure 4. Hand lens
For more information visit: http://www.ipm.ucdavis.edu/
Prepared by Gary Pearson, UC Davis, 2012
Reference: http://entnemdept.ufl.edu/creatures/orn/twospotted_mite.htm#management
Copyright © UC Regents Davis campus, 2012. All Rights Reserved.