2
 The Twospotted Spider Mite
 Both male and femal spider mites develop through the following stages: egg,
 larva, protonymph, eutonymph, and adult. All stages can be found in
 web-covered colonies on the undersides of strawberry leaves. For untrained
 observers, separate n of the various stages is difficult, with the exception
 of the eggs. The e gs are spherical, about 0.14 mm in diameter and clear when
 newly deposited. T ey turn opaque when incubation proceeds. The adults
 usually have a dark spot on both sides of the body, hence their common name.
 In Florida, populati ns of the twospotted spider mite reproduce throughout the
 season. Non-active diapausing) females are reddish and can be found in dense
 colonies. They do n t feed or reproduce.

 Dispersal of the two potted spider mite is mainly by infested nursery stock.
 Consequently, patchy infestations ("hot spots") are characteristic for this
 pest in strawberry fi lds. Mites also can suspend themselves on silken
 threads and be disper ed by air currents; dispersal by field workers is
 possible. These dispersal systems, however, are of minor importance in
 Central Florida.

 Temperature and host lant quality are important determinants for egg
 production as well as for the rate of development. One female may produce as
 many as 100 eggs during her life time; one generation may develop in about 7
 days at 85'F.

 The Predatory Mite
The developmental stag s of the predaceous mites are similar to that of the
twospotted spider mite: egg, larva, protonymph, deutonymph, and adult. Eggs
of Ph. persimilis are a ber and are always deposited in close proximity to the
food source, the spider mite colony. They can be distinguished from the prey
eggs by their amber col r, oval shape, and larger size. Immatures of the
predator are orange, ha e long legs, and are highly mobile.

The more rapid rate of development compared to that of its prey, enhances its
ability to suppress spid r mite populations. The predator may develop from
egg to adult in approxim tely half of the time required for the development of
spider mites under simil r conditions. Therefore, it is not surprising that
this species is a very e fective natural enemy of the twospotted spider mite.
All predator life stages, except the larvae which do not feed at all, feed on
all stages of the twospotted spider mite. They depend entirely on spider
mites as food; they are o ligatory predators and will starve or disperse if
spider mites are unavaila le.

Predatory mites have a hi h dispersal rate and capacity to find prey colonies
in strawberry fields. Th y disperse short distances by crawling from plant to
plant and long distances wind currents. Both systems contribute to a high
searching capacity by the redator.