Common Pests and Solutions
Pests are the No.2 enemy to cacti & succulents lovers, following overwatering (mentioned in another post https://succulents-minwei.blogspot.com/2017/09/planting-and-caring-cacti-succulents.html).
The most common ones in bay area are slugs (also snails) and mealy bugs.
Slugs and snails like to stay in damp shady area. They feed on leaves and fleshy stems. They attack not only succulents, but also cacti in some occasions. They leave ugly holes and tell-tale slimy traces. Below are two examples.
The best solution is to move the plants to sunny area and reduce watering frequency. If possible, don't place the pots directly on soil. I have posted a DIY project to make plant pot shelves (https://succulents-minwei.blogspot.com/2017/09/diy-plant-shelf-from-pallets.html). During moving, check the bottom of the pots to remove the slugs & snails. Also check the backside of leaves. The problem should go away once you do so.
Slug pellets would be the last resort because they may be toxic. Metaldehyde and methiocarb are the most common active ingredients. Whereas methiocarb causes the slug to swell up with fluid and die, metaldehyde damages the mucus cells causing the creature to produce masses of slime and dehydrate.
The mealy bugs like the new shots and fleshy leaves. Over-watering or over-fertilizer may make things worse. Many people suggest to apply soapy insecticide. I have found that the easiest and best solution is to spray 70% iso-propanol (IPA). It is safe without any side effects. It will not only kill the bugs and eggs, but also wash away the white woolly nests. Check the plants in few days after the first spray, if the mealy bugs come back, spray again. Usually after 2-3 times, problem is solved.
Today, cochineal dye (Red #40) is still used as an organic food coloring and in lipsticks and tattoo inks. A famous case is Starbucks dropped this dye in 2012. The company used this dye in multiple drinks (e.g., strawberry drinks), which raised protest from vegetarians and the others who don't want to eat bugs.
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| Moorten Botanical Garden_Palm Springs CA |
The most common ones in bay area are slugs (also snails) and mealy bugs.
1. Slugs & Snails
The best solution is to move the plants to sunny area and reduce watering frequency. If possible, don't place the pots directly on soil. I have posted a DIY project to make plant pot shelves (https://succulents-minwei.blogspot.com/2017/09/diy-plant-shelf-from-pallets.html). During moving, check the bottom of the pots to remove the slugs & snails. Also check the backside of leaves. The problem should go away once you do so.
Slug pellets would be the last resort because they may be toxic. Metaldehyde and methiocarb are the most common active ingredients. Whereas methiocarb causes the slug to swell up with fluid and die, metaldehyde damages the mucus cells causing the creature to produce masses of slime and dehydrate.
2. Mealy Bugs
These bugs are nastier. An infested plant is covered in tiny woolly white nests and sticky honeydew. Below are a few pictures.
The mealy bugs like the new shots and fleshy leaves. Over-watering or over-fertilizer may make things worse. Many people suggest to apply soapy insecticide. I have found that the easiest and best solution is to spray 70% iso-propanol (IPA). It is safe without any side effects. It will not only kill the bugs and eggs, but also wash away the white woolly nests. Check the plants in few days after the first spray, if the mealy bugs come back, spray again. Usually after 2-3 times, problem is solved.
Fact Check
The oldest cultivating cacti was to raise mealy bugs by the Aztecs (in Mexico, from 14th to 16th century). Large quantities of the female cochineal beetles were crushed to produce a rich purple dye, which was used for coloring royal and ceremonial robes. Male beetles yield a brilliant scarlet dye. When the Spanish arrived, they set up plantations and sent the dye back to Spain.Today, cochineal dye (Red #40) is still used as an organic food coloring and in lipsticks and tattoo inks. A famous case is Starbucks dropped this dye in 2012. The company used this dye in multiple drinks (e.g., strawberry drinks), which raised protest from vegetarians and the others who don't want to eat bugs.
好肉麻呀！
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