i recently bought some cacti and a couple of them looked like they were rotting so I pulled them out. however some of the other cacti have white specks on them and are also shrivelling/ turning brown while others are perfectly healthy. what do i do?
The white specks are most likely mealy bugs, so it might be wise to spray them with a systemic insecticide to try and kill them off. Also try to quarantine any plants with bugs, so that they don’t spread to your healthy plants. If any plants are rotting, then cut off any rotten portions of flesh, leave the wound to dry out completely and try to reroot the plant from there. To root a cactus cutting, you pretty much plant the cutting in dry soil mix, and place it in a warm, bright spot. Only start to water cuttings when there are signs of roots forming (lift up the cutting to check for roots every so often).
A very strange relationship of sorts exists between butterflies of the Miletinae Lycaenid subfamily (in this case, the Brownies) and ants - a relationship that allows the adult butterfly and its caterpillars to sit nonchalantly amongst throngs of ants in what would otherwise be a death sentence.
Firstly, the Miletinae caterpillars are carnivorous and feed on sap-sucking Hemipterans such as aphids and mealy bugs. Ants “farm” and defend the same beasts for their sweet nutritious honeydew. So these two worlds inevitably collide.
It has been postulated that the caterpillars (and clearly adult butterflies) have some kind of chemo-mimicry that render themselves ‘invisible’ to the ants. As far as the ants are concerned, the butterflies and caterpillars are perceived as just other ants in the colony.
Strangely, although the caterpillars and adult butterflies of the Miletinae derive 'protection’ from the ants, they give nothing back in return. On top of that, the adult butterflies partake of the honeydew that are secreted by the aphids and mealy bugs, and their caterpillars feed on the ants’ source of food.
So it is hardly fair, but the only losers are the caterpillar’s meals.
Brought home a little Blue Chalk Sticks (Senecio mandraliscae). It’s important to quarantine new succulents, because even the healthiest looking plant may have some stowaways on board. Here are some photos of the process I use to comb through my new buddy.
The simple antiseptic and q-tips I use to kill any pests I find.
The biggest mealy bug nest I’ve ever seen! The little grey specks are the mealy bugs and the cottony white is the nest. There were several smaller nests at the base of other leaves, but my camera couldn’t focus on something that tiny. It’s important to wear your glasses when doing this, folks!
A few scale insect marks. They look like little grey scabs or pimples, but they’re little shields. A scale bug will chew a small hole in a succulent leaf and close it up with this shell to protect it while it feasts on the plant’s sap. To rid your plant of these pests you need to use some tweezers or a fingernail to scrape off the scab, then dab it with the antiseptic cotton swab. It may leave a scar, but it’s better then an infestation. They’re drawn to shady parts of the plant, so make sure to check the interior!
A huge mealy bug on my cotton swab. I’ve seen some 1/5 this size, so they can be hard to spot. It’s difficult to tell if the tiny ones are bugs or dirt, but here’s a tip: they turn red when they come in contact with the antiseptic. Make sure to get them all, and their nest, or they’ll just come back.
Once it’s all de-bugged try to rinse off any excess alcohol. Some plants have sensitive skin.
I have not been taking pictures of anything that’s going on with my plants lately due to mealy bug problems and working a lot. I just wanted to show a few of my violets that are blooming, as well as some of my other plant room mates that are looking especially nice. I’ll save them for another post. I’m also including my Episcia and my Alsobia here since they’re related. See below the break..
Hi! I think that my cactus has mealy bugs, and my friend referred me to you. What can I do for it? What kind of insecticide do you recommend?
Where you live will determine what products are available to you. See what’s available in your country and try to choose a systemic product which is made for ornamental plants. Apply it according to the manufacturers instructions. In the UK, Bayer’s Ultimate Bug Killer is what most collectors use. In Germany (and no doubt many other parts of the world), there are some dimethoate-based products available, which are incredibly effective against mealybugs. In the USA I believe Malathion is available, which is also highly effective.