Monday, December 12, 2011

Green Pesticides, Natural Pesticides: What Are They and Do They Work?

The term "green" has become a big buzz-word in the pest management industry. So what exactly is a green or natural pesticide? Green or natural pesticides are pesticides derived from substances found in nature. These may include pesticides derived from inorganic minerals - like boric acid, limestone, and diatomaceous earth - as well as pesticides derived from botanicals, such as pyrethrum and limonene. Today, more than ever, people are concerned about the impacts traditional, synthetic pesticides may have on the environment. So it's easy to see why people want to use green pesticides. In addition, many of the green or natural pesticides are classified by EPA has Category IV pesticides. Category IV pesticides are exempt from notification. This makes green pesticides attractive for use in school settings.

What you need to know is that while many green "spray" pesticides work on contact, they have little to no effect once they dry. In other words, they don't persist in the environment for very long; that's part of what makes them "environmentally friendly!" So if you're using a natural or green spray pesticide, for best results, you need to spray the bug directly. This is okay if you're dealing with an occasional cricket, ant, or other insect that wonders in. But in some cases, you may need to use a pesticide that persists a little longer.

Some of the naturally derived dusts, such as boric acid and diatomaceous earth, do have a long-lasting effect (if they are not displaced after application). But NEVER use pool grade diatomaceous earth; it is an inhalation hazard and should only be used for swimming pools. To be sure you're using the right product, only use pesticides registered with the EPA. And you should always use caution when applying dusts. Follow the label instructions carefully and always wear gloves and a dust mask. Indoors, dusts should be applied in cracks & crevices and voids, NOT along baseboards or other open places. Many dusts can be applied outdoors as well, but again, follow the label instructions. To avoid drift, never apply dust in windy conditions.

Many of the synthetic pesticides also have longer residual activity. There are certain instances when it's necessary to use a pesticide that will persist in the environment for some time. For example, with pests like cockroaches, which spend most of their time hiding in cracks and crevices, a longer-lasting pesticide will most likely be necessary. After all, how can you spray roaches directly with a green pesticide if you never see them?

Really, it's a delicate balancing act. So, here's my advice when it comes to using pesticides, whether it be green or synthetic (really, it's just using IPM):
  • First, take steps to eliminate potential food and water sources, limit harborage areas, and pest-proof buildings to keep pests out.
  • Use insect baits preferentially over other pest management products (when dealing with roaches and ants). 
  • "Green" spray insecticides can be used as contact sprays to apply directly to insects.
  • "Green" insecticidal dusts can be used in cracks & crevices and voids. Always apply dust in a thin, even manner - don't dump it in piles - insects will actually avoid piles of dust. 
  • If you deem it's necessary to use a conventional, synthetic pesticide, ALWAYS read and follow the label instructions carefully. Try to limit your applications to cracks & crevices and avoid broadcast applications indoors (remember, crack and crevice applications are also exempt from notification). This will limit the potential risk of exposure to students and staff. 
In general, green pesticides are less toxic than conventional, synthetic pesticides. But as with ANY pesticide, green pesticides can be toxic if not used properly. Just because the active ingredient is "all natural," it's not okay to use more or in areas not listed on the label. Always read and follow label instructions, regardless of what type of pesticide you choose.
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