Siphotrol Plus II Review

siphotrol plus ii review


Siphotrol Plus II by Vet Kem is an insecticidal premise spray. It controls fleas and other domestic pests. Siphnotrol contains pyrethrins to rapidly kill adult fleas. It also contains an insect growth regulator, (s)-methoprene, to prevent eggs and larvae from developing into adults. Methoprene remains residually active indoors for 7 months, effectively preventing re-infestation.

Other premise sprays are similar to Siphotrol. They all contain similar active ingredients, and in similar formulations. Thus, they all preform about the same. They all have high ratings on, as one would expect. The primary difference between premise sprays is price, and Precor 2000 Plus is the best value.


Siphotrol Plus II
Product Information Chart

Size16 ounces
Capacity2000 sq ft
ApplicationAerosol Spray
Use OnHome Premises
KillsAdults, Eggs & Larvae
Treatment Duration7 months
Ingredients0.085% (s)-methoprene
0.350% permethrin
0.300% phenothrin
2.000% MGK 264
1.400% piperonyl butoxide
95.865% other ingredients
Product Labelview

*prices are based on at time of publishing

Active Ingredients


Vet Kem’s Siphotrol Plus II contains (s)-methoprene, also called Precor. This compound is an insect growth regulator (IGR). IGRs work by mimicking naturally occuring hormones in insects, specifically juvenile hormone. When an insect is exposed to an IGR, it can’t molt into the next stage of life. Flea eggs and larvae can’t complete their metamorphosis into adults. And adult female fleas are sterilized. IGRs are considered safer conventional insecticides, because they specifically mimic insect hormones.

Methoprene is the most important active ingredient in Siphotrol. 95-99% of flea populations consist of eggs, larvae and pupae. The immature fleas reside in the environment, usually at the base of carpeting. Adulticides are ineffective in killing these stages. The insecticidal spray can’t penetrate carpets to the depth where fleas live. Plus, adulticides have a short-lived effect. IGRs, such as methoprene, remain active for 7 months indoors. Because carpets are such a difficult surface to treat, long-lasting residual activity plays a crucial role is controlling fleas.

Permethrin & Phenothrin

The adulticides in Siphotrol are permethrin and phenothrin. These are two pyrethroids, synthetic compounds based on the chemical structure of a botanical insecticide found in Chrysanthemum flowers. Pyrethrins and pyrethroids are commonly employed to kill adult fleas and other insects in homes. These insecticides are neurotoxins, affecting the insect’s nervous system by causing spasms, paralysis, and death.

When Siphotrol Plus II is sprayed, exposed adult fleas will be quickly killed. Unfortunately, only 1-5% of flea infestations are adults. Some adults can be found emerging from their cocoons in the environment. However, once they find their way onto a host, the fleas stay there. Thus, there won’t be very many adult fleas in carpets at any one time.

Most of the immature fleas living deep within carpets won’t be affected. The carpeting provides refuge from insecticide penetration and vacuum removal. As a result, the fleas currently developing in the environment may survive to emerge as adults. This can confused those who just sprayed. However, the young lives in the carpet at the time of spraying will be the last generation. Any eggs thereafter will become sterilized when they fall onto the IGR-treated carpets.

Piperonyl butoxide & N-octyl bicycloheptene dicarboximide

Synergists don’t have insecticide properties, but will enhance the potency of pyrethroids. As a result, they’re often found in pest products together. Synergists allow less insecticide to be used, which results in safer and cheaper products. The two most common synergists are piperonyl butoxide and N-octyl bicycloheptene dicarboximide (MGK 264). Both are included in Siphotrol.

Comparison to Competitors

Siphotrol’s main competitors are Precor 2000 Plus, Ultracide, and Virbac Knockout. All of these products are comparable in quality and efficacy, because they’re aerosol premise sprays with similar active ingredients and concentrations. All four sprays are highly rated on reviews. Price is the most noteworthy difference between them, and Precor 2000 Plus is the cheapest.


The following instructions were taken from the product label of Siphotrol Plus II. Before using the product, view the label for the full directions and precautionary statements.

It is a violation of federal law to use this product in a manner inconsistent with its labeling.

General Information

Siphotrol® Plus II Premise Spray (Siphotrol® Plus II) kills adult fleas, hatching flea eggs, flea larvae and ticks. PRECOR®, the unique ingredient in Siphotrol® Plus II, provides 30 weeks’ protection by preventing eggs from ever developing into biting fleas. For best results, use Siphotrol® Plus II with Vet Kem® on-animal products for complete control of fleas and ticks.

For use in the home/garage/kennel. Not for use on humans or pets. Shake well before use.


Identify treatment areas, especially those where pets frequent, such as in and around pet’s sleeping and resting areas. These are the primary areas where fleas, their eggs, and ticks are found. Before treatment, make a test application to upholstery, drapery, light-colored, delicate fabrics, or wood surfaces in an inconspicuous place.

Prepare treatment areas. Cover all food processing surfaces and utensils during treatment or thoroughly wash after product use. Cover or remove exposed food. Remove pets and cover and unplug aquariums before spraying. Remove motor vehicles before using in garages. For best results with Surface/Carpet treatments, vacuum thoroughly before spraying and discard vacuum bag in outside trash. This product may also be used for infested surfaces inside motor vehicles.

Apply treatment. For flea/tick infestations, a single can treats 2,000 square feet. Hold container upside down 2-3 feet from surface, point actuator towards the surface, and push button. Using a sweeping motion, apply a light uniform spray to all surfaces of furniture, rugs, carpets, drapes, and around all pet resting areas. Avoid thoroughly wetting surfaces. Mist treated areas only until “slightly damp”. Do not over-treat. Reapply in 14 days, if necessary. IMPORTANT: Only complete and proper application to carpets, upholstery, drapes, and other fabrics will provide thorough flea/tick elimination. Keep people and pets out of areas during treatment. Vacate room after treatment and ventilate until surfaces are dry before reoccupying.

For best results, eliminate fleas/ticks on your pet with appropriate Vet Kem® on-animal products.

Storage and Disposal

Storage: Store in a cool, dry area. Do not transport or store below 32° F.

Disposal: Do Not Puncture or Incinerate! If empty: Place in trash or offer for recycling if available. If partly filled: Call your local solid waste agency for disposal instructions.

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