The world seems to be divided into two camps that border on the fervor usually associated with religious cults when it comes to the use of insecticides. One camp claims that there should be no impact on the environment and materials used should be nontoxic. The other camp’s view is that whatever it takes, kill the varmints. Both views have problems.

The no harm school has a philosophical problem. If you find that your precious bonsai is being devoured by Blue-eyed Leafmunchers, you have to realize that they are as much a part of the environment as you are. If you provide them with a lovely salad in the form of your bonsai, it is not their fault. Even if you deal with them by carefully lifting them off your bonsai and tossing them over the fence into the neighbor’s bushes, you are impacting the environment. Also, the idea of a material being nontoxic is a myth. For example, consider water. It is generally considered to be nontoxic, but if you decide to swim to Hawaii instead of flying there on your next vacation, you probably will not make it due to the toxic effect of water in your lungs, aka drowning.

The kill the varmints view has a physical problem to deal with. Most of the heavy duty insecticides fall into three broad classes of chemical compounds, organophosphates, carbamates and pyrethroids. All act by blocking the juncture between nerves and muscles. In recent news there was an item about the alleged use of poison gas in the Middle East. Although the gas is a far more dangerous material than most insecticides, it is an organophosphate which acts by blocking the juncture between nerves and muscles just as insecticides do. The trick in using the heavy duty insecticides is to kill the bugs and not yourself, or the family dog for that matter.

How should we treat the question of insecticide without engaging in pseudo religious mantra? First of all, recognize that bonsai as a group of plants are not usually bothered by insects and that is a great blessing. As a start in managing bugs, keep the area clean where you grow your bonsai. Fallen leaves and trash in general provides a great hiding place for bugs.

The first approach to dealing with bugs is from the Zen school. Here you acknowledge that the bugs have just as much right to live as you do and the correct approach is to do nothing. This works well if your problem is a transient grasshopper or a wandering snail, but falls a bit short in most cases. Once bugs find a lovely dining spot, they quickly send for all their relations, and soon the infestation becomes far more difficult to deal with. As an example, an infestation of scale can grow quickly and may impact the health of your tree to the point where the tree may not survive. However you plan to deal with bugs which find their way onto your plants, the sooner you start the better. Frequent inspection of your trees for bugs pays great dividends.

The simplest way to deal with a few species of bugs such as aphids is to simply wash them off with the hose. This does not work well with many bugs such as scale, and chemical attack is called for.

Any form of chemical control is usually not completely effective with the first application because bugs hide under leaves, in the bark, or in the soil, and so a few are usually not reached on the first application. Whatever you use for control, carefully inspect your trees to be sure that retreatment is not required for complete control.

Some forms of scale can be dealt with by brushing them with a cotton swab soaked in rubbing alcohol. This works well on the bugs that you can see, but there may be some hiding where you can’t see them so you have to keep at it to get them all. Next up the scale of chemicals is safer soap as well as agricultural oil, a form of specially treated mineral oil. Both are relatively nontoxic and can be safely handled with minimal precautions. These relatively gentle treatments are not effective with a few insects such as spider mites, and stronger insecticides are required for control.

Bayer chemical company now markets a so called three in one insecticide which is a mixture of three products, an insecticide a miticide and, for good measure, a fungicide. This product is very effective for a wide range of ills which might befall your bonsai, but also affects the “good” bugs that eat the “bad” bugs, which you would like to avoid if possible. If you choose to use this product, best to spray only the specific tree affected.

The use of powerful insecticides brings up the question of safe handling of the more potent insecticides. These products can be absorbed through the skin, and so you should avoid contact with them by using gloves. The local drug stores sell inexpensive exam gloves made from nitrile rubber which work well. These gloves, incidentally, are useful when you do wood finishing because they are resistant to attack by paint, varnish and stains. Materials that are absorbed through the skin are also rapidly absorbed in the lungs, so inhalation of droplets of insecticide spray should be avoided. Here, paper masks, again available at local drug stores, are a great protection. Although the insecticides available on the market can be toxic if not used with some care, rest assured that they will not jump out and bite you, and with a little thought they can be safely handled.

California is blessed with a master gardener program which fosters a responsible approach to insect control. They may be accessed through their web site for help in identifying insects and specific methods of control. The web site also includes much information about the general care of plants such as fertilizer requirements. Although the information is directed to plants in general and not specifically to bonsai, there is still much of value to bonsai growers. The web site is www.camastergardeners@ucdavis.edu