Spider mites

A pest that many growers fear? That must be the tiny red-coloured spider mite. The most common species are the two-spotted spider mite Tetranychus urticae and the carmine spider mite Tetranychus cinnabarinus. These are plant feeding mites that are present on several crops all over the world. In dry and warm climates, the spider mite population develops rapidly. Time to save your crop with biological control!

What damage can spider mites cause?

• All mobile stages feed on plant sap.
• On the surface of the leaf, you can spot yellow dots as the empty plant cells turn yellow.
• The plant gets out of physiological balance due to a smaller photosynthetic area.
• Leaves turn yellow and the plant might wilt or die.
• The webs made by spider mites also reduce the esthetic value of ornamentals.

How to control spider mites?

For biological control of spider mites, you can introduce:

• Predatory mites such as Phytoseiulus-System and Californicus-System;
• Predatory gall midges such as Feltiella-System;
• Nymphs of predatory bugs such as Macrolophus-N-System.

What are the characteristics of the spider mite?

• The first spider mite populations appear in warm and dry areas of your crop.
• The small eggs of 0.14 mm are spherical round, white-coloured and laid at the bottom of the leaf.
• The tiny larvae are colourless and have 6 legs.
• The nymphs are green with 2 body spots and 8 legs like the adults.
• The colour of the oval shaped adults of 0.5 mm can vary from yellow-brown to red-brown, depending on the crop.
• Hibernating females turn orange-red, hide in the greenhouse and reappear early in the next season, which makes them very difficult to control in this stage.

What about the spider mite’s life cycle?

• Female adults start laying eggs 0.5 to 3 days after hatching and lay eggs for 10 days at 35 °C/95 °F up to 40 days at 15 °C/59 °F.
• During warm and dry weather spider mites reproduce fast and lay about 100 eggs under optimal circumstances.
• Spider mites have 5 development stages: egg, larva, 2 nymphal stages and adult.
• It takes them about 7 days to develop from egg to adult at 30 °C/86 °F, 17 days at 20 °C/68 °F and 36 days at 15 °C/59 °F.
• Fecundated females go into diapause in autumn, when temperature and photoperiod drop.