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Two Spotted Spider Mites
Two Spotted Mite Description
The two spotted spider mite is quite small (< 1/60 in.), oval-shaped,
has 4 pieces, 7 legs, and is yellowish or greenish with two dark spots
on its back which are composed of food contents. Males are slightly
smaller (1/80th in.) and slimmer than females with a pointed abdomen.
The eggs of the two-spotted spider mite are pearly white, circular, and
on the webbing on the foliage. Young mites resemble the adults except in
size and possess only 3 pairs of legs in the first stage. Later they
develop a fourth pair of 7 legs. The immature mites pass through three
stages before becoming adults.
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Spider mites can cause extensive damaged
leaves. Leaves turn from dark green to pale or bright yellow.
Two spotted mites, eggs (round balls) and
adults.
Rose leaf damaged by Spider mites.
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Life Cycle
Spider mites attack many species of plants including common
greenhouse crops such as tomatoes, carnations, chrysanthemums,
snapdragons, violets, roses, and fuchsia. Spider mites may be found on
any part of the plant, but most often are on the middle-aged leaves.
Under severe infestations, they may be found on the growing tips.
Generally, the lower leaf surface is preferred over the upper surface.
Egg laying and development is affected by temperature. The optimum
temperature for egg laying is 30 degrees C with an individual female
laying 100 eggs and living for 30 days. Under these conditions, a new
generation is
produced every eight days. Under low temperatures (21 degrees C)
development may be slowed taking 14 days for a generation and at 12
degrees C the process may extend to 40 days. Under optimum conditions, a
female mite may produce 13 million offspring during her
lifetime. Spider
mites are most damaging under greenhouse conditions of high temperature
and low humidity. |
Plant Damage
Damage caused by the two-spotted spider mite will vary according to
the infestation level however, mites feed by piercing plant cells with
their mouthparts and sucking out the cell contents. Lightly infested
plants will have foliage with pale blotches or spots showing through the
leaf while with heavy infestations the entire leaf appears light in
color, dries up, and often turns a reddish-brown with blotches in and
around the edges. Plants generally lose their vigor and die. Silken
threads will also be present among the foliage. The mites will be
located on the underside of the foliage and appear as tiny, reddish,
greenish, yellowish, or blackish, moving dots. The mites' color appear
to be related to the type of host plant.
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