Description
Rhyzobius (also known as Lindorus) is a scale eating lady bird beetle. They were introduced to California from Australia in the 1890’s to control black scale. Adults are small 2mm long with black to dark reddish-brown wing covers, a reddish-brown head, legs and thorax. The eggs are oval, pale yellow to whitish, about .7mm long and are deposited under scale insects. The larvae are dark brownish to black on top, pale underneath and covered with numerous short hairs. Larvae are 3.5 mm long when mature. The oval black or dark gray pupae are distinctly segmented and the size of the adults.
Target Pests
Hard scale, soft scale, mealybug, and numerous insect eggs.
Life Cycle
The adult females lay several hundred eggs during their lifetime, depositing them in groups of 6 to 10 under the bodies of scale insects. As larvae hatch and grow, they feed on small scale crawlers and eggs for about 3 weeks until they pupate. Adults live about two months, feeding on all life stages of pests. Optimum conditions are 68°-86°F with relative humidity over 60%, although Rhyzobius have been observed feeding in temperatures as low as 40°F.
Use in Biological Control
Effective in orchards, landscapes, Christmas tree farms, greenhouses and interiors.
Rates are 2-10/10 ft² or 10-40 adults/tree.
Each adult female Rhyzobius consumes about 100 soft scale nymphs or 200 soft scale eggs during her lifetime and about twice that number or more if feeding on armored scales.
For Best Results
- Rhyzobius are difficult to scout. Look for scales that have been partially eaten or with ragged holes chewed in them.
- Rhyzobius have trouble with too much honeydew as it hinders their movement. Wash honeydew off plants before releasing.
- Control ants as they may defend scales from predators. Use barrier products or boric acid to control ants.
- Remove sticky traps near release areas to prevent Rhyzobius from getting stuck.
- Release as soon as possible, evening is preferable. Do not store in refrigerator.
