CACTI AND SUCCULENTS PESTS
Many common pests can be controlled by use of systemic insecticides, contact insecticides, insecticidal soaps and, in some cases, natural predators. Systemic insecticides are very effective as they are absorbed by the plant, making its sap poisonous to the pests. However, they are also toxic to people and absorbed through the skin in the same way.
Very common pests of cacti and succulents, and potentially a huge topic, are MEALY BUGS. There are many species of mealy bugs, but these insects are all small and hard to identify. They are also very aggressive and annoying and first in group are – RISPERSIA FALCIFERA (root mealy bug), PSEUDOCOCCUS and ERIOCOCCUS (fleecy mealy bugs), as well as most dangerous DIASPIS ECHINOCACTI.
All of these species are fast propagating even in earliest life forms, they are very mobile, hard recognizable and because of that they spread very fast. Adult speciments are inert, protected with shields, fibers or wax secretes, parasiting attached to plant tissue. Usualy we notice them after they multiply and make a lot of damage.
Root mealy bugs are very common pests of cacti and succulents, but are found only on the roots of infested plants where they do considerable damage. This may lead to the plant rotting where the damage allows fungal or bacterial infections to enter the plant tissues. They produce powdery white or white fluffy deposits in the soil which may sometimes also be seen underneath the pot. Dry cacti substrate is appropriate for root mealy bugs living condition.
For prevention ground up moth balls added to the potting mix seem to discourage infestation by root mealy bug, and probably discourages other insects. However, the chemicals in the moth balls can cause damage to plastic plant pots and are best used with clay pots.
Eliminating mealy bugs can be effective by using regular applications (weekly for several weeks) of insecticide watered into the soil, or immerse the plant pot up to the top of the soil in a bucket of insecticide with a couple of drops of washing-up liquid to help wetting of the soil. In the South Europe, you can find such insecticides like KONFIDOR or PRESTIGE, but they probably have different names in your surrounding. Watering with the substitutes is esspecialy effectin in autumn. Be sure to carefuly read all manuals (labels), because some preparats can be used only with specific plants and others can color your plants. The plant absorbes insecticide and that affects not only root, but all mealy bugs that consume plant tissue.
Spiders, mites, snails
The mites are exceedingly small and a strong magnifying glass is needed to see them clearly. An early sign of their presence is the appearance of brown dots where the plant epidermis has been damaged, merging into confluent scarring and sometimes webbing on the plants. The harmful microscopic red spider mites, which damage plants, should not be confused with a commonly seen, much larger red mite 2-3 mm across which is a harmless predator.
The reddish-brown mites thrive in hot dry conditions and dislike humid conditions, so overhead watering and spraying plants may discourage mite attack. Red spider mites can be biologicaly controled by a predator Phytoseiulus persimilis. It requires temperatures over at least 70°F (21°C). It is difficult to obtain a predator/prey balance that allows long-term protection in a small collection.
Aloe mites are tiny mites causing abnormal, irregular bumpy growth on all parts of Aloes. The only way to eliminate this bugs is to cut out and burn all diseased parts in the early stages, or the whole plant will soon be in a serious infestation.
Snails are less traditional pests of succulent plants, they can be extremely destructive if they get into a collection. although unlikely to invade the house, beware of carrying them indoors on the sides of a pot or hidden under a plant. Snails find easy access to greenhouses and cold frames via vents, cracks in the structure and doors left open. Generally, careful inspection will allow the culprits to be picked off plants and pots by hand. Maybe you don't want to kill this creatures, but if you want to protect your collection - take them at least 200 meters away (220 yards).