How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PESTS

Thread-footed mites are tiny and cannot be readily seen without magnification (20X to 40X). The life stages of these thread-footed mites are: egg, nymph, pseudopupa, and adult (one less stage than for spider mites). Eggs of the cyclamen mite are one-half the length of the adult and are oval shaped. Eggs of the closely related broad mite are distinguishable from cyclamen mite eggs by rows of white pegs on the egg's upper surface. Immature stages of these mites are white.

These mites get the name "thread-footed" from the appearance of the hind pair of legs in the adult female, which is threadlike; adult males, on the other hand, have stout legs for clasping the female. Adult males carry female pseudopupae on their back. As soon as the adult female emerges, they mate.

Cyclamen mite is generally found feeding on growing terminals, in buds, or on unfolding leaflets. Their development is optimal under moderately warm (60° to 80°F) temperatures and high humidity (80 to 90%). Broad mite is similar to cyclamen mite, but is generally found mostly on the undersides of plant leaves. Mites disperse between plants on air currents and by mechanical transport such as on worker's clothing. These mites can complete one generation in 7 to 21 days, depending on temperature. Female bulb scale mites lay up to 28 eggs. Adults are usually found between the scales of the bulb and the neck region. Bulb mites overwinter in bulbs between the scales, emerging as the leaves grow. They re-enter bulbs as the bulbs dry in the field. One generation can be completed in about 7 weeks under field conditions.

DAMAGE

Feeding by cyclamen and broad mites is easily recognized on all hosts because affected leaves become characteristically cupped, dwarfed and thickened, and the internodes are greatly shortened. Broad mite damage occurs more generally over the plant than cyclamen mite damage. Bulb scale mites feeding in developing shoots can cause longitudinal bronze streaks of discoloration, horizontal cracks, distortion, and death of leaves and flowers.

BIOLOGICAL CONTROL

Neoseiulus californicus and other species of predatory mites have been used for broad mite and cyclamen mite control.

CULTURAL CONTROL

Because these mites feed on a large variety of plant species, keep production areas free of weeds that can serve as hosts for mite populations. Carefully inspect plants being brought in to start a new crop to ensure that they are free of pests, and disinfest the plants if needed. Disinfestation can be accomplished by immersing propagation stock in 110.3°F water for 30 minutes, or treatment at 100% relative humidity and 110.3°F for 1 hour. If hot spots of these mites are found in production areas, consider roguing affected plants and treating the surrounding plants.

MONITORING and WHEN TO TREAT

Visually inspect plants for typical damage symptoms as part of a weekly scouting program.

TREATMENT

Selected Materials Registered for Use on Greenhouse or Nursery Ornamentals
Read and follow the instructions on the label before using any pesticide. Before using a pesticide for the first time or on a new crop or cultivar, treat a few plants and check for phytotoxicity.

PUBLICATION

UC IPM Pest Management Guidelines: Floriculture and Ornamental Nurseries
UC ANR Publication 3392
Insects and Mites
K. L. Robb, UC Cooperative Extension, San Diego Co.
H. S. Costa, Entomology, UC Riverside
J. A. Bethke, Entomology, UC Riverside
M. P. Parrella, Entomology, UC Davis
Acknowledgment for contributions to the insects and mites section:
R. S. Cowles, Connecticut Agricultural Experiment Station, Windsor, CT

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