Pests

Pests come in all shapes and sizes, from the sub-microscopic viruses and microscopic pests such as mites, bacteria and fungi, through to aphids, cockroaches, snails and large mammaliar menaces. In most cases orchids do quite well against pests; even an infected plant can show vigour and even flower given a mild infestation, but without the pests they would likely be doing much better.

Most pests can be easily reduced or avoided; the only real terror is the virus - once your plant has a virus, it's got it for life. And even worse, the other pests can help spread it.

The list below has been categorised by the function that the pest has on the plant, so the symptoms and damage is similar between the pests, differences will be listed against the pest..

Mechanical Pests

These pests will eat the flowers, leaves and roots of the plant. The damage can occur quickly and without warning; many pests will favour young shoots and flower spikes, which can be disappointing for the grower and can set the plant back, however most plants will bounce back quite readily once the pest has been removed. 

Cockroaches

Cockroaches can eat any part of the plant, and mainly are attracted by rotting growth or media, but can also be attracted by flowers or feed opportunistically. They can carry viruses due to their larger size and ease of movement. Prevention is the best approach, by reducing litter in the growing area and ensuring that growing media is not stale (e.g. does not smell rotten and is not clumped). Household pesticides, such as sprays and baits, can be used to eliminate pests and provide a barrier around the growing area. Spreading diatomaceous earth in the growing area can also be used to deter cockroaches though it rarely kills them. 

Caterpillars

Caterpillars eat mainly leaves, buds and sometimes stems. They are carried in by moths and butterflies, and their eggs can be seen hanging from threads on the underside of leaves. They can act quickly so it's important to remove them as soon as they are found. Eggs can be removed by rubbing fingers or a cloth against the area and caterpillars are best cut in half with a pair of scissors/secateurs, or squashed. Importantly, wash and disinfect any instruments used to cut the insects, especially if using them for trimming plants as well.

A systemic pesticide used for eliminating caterpillars from vegetables can also be used as a preventative measure on orchids during spring/summer.

Snails, Slugs

These bandits are very good at hiding and there's usually a few in each collection. Often they are harmless, eating dead or dying leaves, or breaking down the sheathes around pseudobulbs and flowers, but every now and then you'd get a nasty one, or a bunch of nasties, that will get into the buds, leaves, and flowers, leaving unsightly marks on mature growth and destroying young growth.

They can be managed using pellets, however often pellets can get into the media and go mouldy, which can cause fungal and bacterial issues for the orchid. the best thing to do is lay pellets around pots and on the floor of the growing area. The best pellets to use are iron chelate based; the green pellets can poison pets and usually break down faster.

Even when using pellets, there will be survivors. Any survivors should be killed on sight by squashing them. Throwing them may cause injury but not death, so always squash. 

Millipedes, centipedes, earwigs

These critters usually aren't an issue as they only eat rotting matter such are the media and dead roots, but they can carry viruses and occasionally can eat the roots right down to nothing. They can only be removed by repotting the orchid, though can usually be killed quite easily by drenching in a solution of pyrethrum spray or shaking some diatomaceous earth through the media.

Dogs, cats, mice

These critters are uncommon but can be an issue, especially mice. The best option is to prevent them in the first place by ensuring the growing area is well protected and contained. A greenhouse for example is great; running chicken wire along the bottom 60cm of a shadehouse exterior walls will help along with installing a door.

Otherwise, mouse traps and whatnot can be used for mice/rats. Dogs can be easily trained with some vigilance and only allowing them to enter the growing area when supervised. Cats, especially neighbours' cats, can be a nuisance but they often dont eat the plants, instead they can knock them over or damage them by moving around the growing area. Making the area less attractive or providing a more attractive area for them by planting catnip or providing shelter etc may help.

Sucking Pests

* Midges

* Scale

* Mealy Bugs

* Aphids

* Spider Mites

Carriers

* Ants

Systemic Pests

* Fungus

* Bacteria

* Virus