I will be discussing two basic topics, pesticides and pesticide formulations.

PESTICIDES The following are the eight major groups of pesticides.

Botanicals: Botanicals date back many centuries. One of the first pesticides were dried and crushed chrysanthemum flower that were used to create Pyrethrum . Today this is used in many general insecticides as well, as in flea and tick shampoo, lice shampoo, and mosquito repellents. This is available as an unrestricted pesticide in several formulations. Botanicals normally have added to them a synergists that will work with the pesticide to increase the insecticidal effect. Natural botanicals can usually be broke down by the insect and, within a few hours, the insecticide will have no effect on the insect. Synergists help to prolong the effect of the Pyrethrins so it will work better. Pyrethrins effect the insect by interfering with the function of the nervous system, yet have a very low level of toxicity to mammals. However, be careful of any fish, birds, reptiles, and amphibians that may be near the treatment area, as they tend to be sensitive to just about all insecticides.

Synthetic Pyrethroids Chemists have been able to synthesize insecticides to mimic the behavior natural pyrethins. These are called synthetic pyrethroids and they generally have some form of improved action compared to natural pyrethrins. Sample lists of these insecticides include allethrin (Pynamin), cyfluthrin (Tempo), fenvalerate (Tribute), permethrin (Dragnet, Torpedo), and remethrin (SBP-1382). Some of these insecticides are available for unrestricted use.

Inorganic These are typically some kind of mineral that has very long residual properties with typically slow knockdown rate (rate where the insects are killed after contact). Some of these insecticides include borax, boric acid, diatomaceous earth, precipitated silica (Drione, DriDie), and sodium fluoride. Some of these insecticides are available as unrestricted.

Organophosphates These types of chemicals inhibit an important enzyme that controls the nervous system called cholinesterase. If this enzyme is inhibited, the communication of nerve impulses between nerve cells is disrupted, eventually causing death. Use of these chemicals should be done with caution because mammals, including cats, dogs, and humans, also contain cholinesterase which can be effected in the same way as insects. However, if used carefully, today's organophosphates are relatively safe compared to those used in past decades. Some of the common organophosphates include acephate (Orthene), chlorpyrifos (Durban), propetamphos (Safrotin), and malathion (Cythion). Some of these products can be found in some unrestricted insecticides.

Carbamates Carbamates attack the nervous system the same way as organophosphates. These, however, generally have a lower toxicity to mammals than organophosphates. These insecticides include bendiocarb (Ficam), carbaryl (Sevin), and propoxur (Baygon), all which are restricted use pesticides.

Chlorinated Hydrocarbons These were the first synthetic organic insecticides that were created. Therefore, their method of action is very similar to that of the pyrethrins and synthetic pyrethroids. The best known was DDT. Another common chemical in this category was chordane. These, and many other chlorinated hydrocarbons, are now banned. Those that are still used, at least in some states, are restricted use pesticides and they include lindane, methoxychlor and dicofol.

Fumigants These groups of chemicals are active as gases and vapors. These gases are generally very penetrating. Two that are generally available to consumers are naphthalene and paradichlorobenzene, generally found in mothballs. Other fumigants, which generally require the structure to be tented, and are restricted use pesticides, are phosphine, methyl bromide and sulfuryl fluoride.

Insect Growth Regulators (IGR's) This group of insecticide prevents the reproduction and / or growth of insects. The toxicity to mammals is very low because they act by disrupting processes that are distinctive to insects. Some IGR compounds are available only to certified pest management professionals, but many baits and insecticides available as unrestricted use contain some amounts of IGR's. When a container advertises that this product also kills the eggs (or prevents eggs from hatching, etc.), this usually means that an IGR has been added.

PESTICIDE FORMULATIONS Just as important as the type of pesticide is the formulation of the pesticides. Formulations have to deal with whether they are dry formulation such as powders, dusts, granules, etc. or wet formulation such as concentrates or sprays.

Liquid formulations include emulsifiable concentrates, solutions, flowables, flowable microencapsulated formulations, ready-to-use sprays, and some fumigants. Generally, unrestricted liquid insecticides fall into the ready-to-use category.

Dry formulations include dusts, wettable powders, soluble powders, baits, granules, pellets, and some fumigants. The unrestricted ones in this category are the baits, granules, pellets, some dusts, as well as moth balls (fumigants).

RODENTICIDES Rodenticides have their own formulations and are specifically designed to target rodents such as mice and rats. Therefore, we will deal with these pesticides separately. Rodenticides fall into two basic types; anticoagulants and non-anticoagulants.

Anticoagulants effect the rodent by causing them to bleed internally. These can be very dangerous if consumed by pets or children. Most rodenticides today are of this type. Some of the anticoagulants include brodifacoum (Talon, d-Con, and others), bromadiolone (Maki, Contrac), chlorophacinone (Rozol), warfarin (d-Con and others) and diphacinone (Ramik). Some are available as unrestricted pesticides.

Non-anticoagulants effect the rodents in various ways. Bromethalin (Assault, Vengeance) effects rodents by disrupting the energy production within the cells resulting in a buildup of fluid, especially around the spinal column and brain, causing paralysis and death. Cholecalciferol (Quintox) effects rodents by increasing calcium causing hypercalcemia. Others include strychnine, zinc phosphide, flouroacetamide, and sodium fluoroactate. Most of these pesticides are available only as restricted pesticides while some are not available.

Rodenticide formulations fall into the following three categories: BAITS: Perhaps 95% of all rodenticides used fall into this category. These baits come as palletized baits, loose meal baits, packet-style baits, paraffin block baits, liquid baits, and fresh baits. Generally, packet-style baits, containing pellets or loose meal baits, are what is available as unrestricted. TRACKING POWDERS are used by pest management professionals and can be very toxic. They are used when a rodent population is resisting the other baits. They are injected into voids, the rodent get the powder onto their feet, and when they wash off their feet, they consume the bait. FUMIGANTS are rarely used for rodent control unless there is a large infestation. These are extremely dangerous and should only be done when justified and done by an experienced professional.

Even when a pesticide is used properly, the consumer should always be on the alert for problems and symptoms associated with pesticide poisoning. SEE PESTICIDE SAFETY AND POISONING for more information.

If you have any questions, please ask Pestdude!

See also:

CHOOSING A PEST MANAGEMENT PROFESSIONAL