Brand: RAVAP ™ EC


FORMULATION: liquid concentrate for spraying animals or farm premises


  • Dichlorvos: 5.3% = 50.3 g/L
  • Tetrachlorvinphos: 23% = 230 g/L

CHEMICAL CLASS of the active ingredient(s): Organophosphates


PARASITES CONTROLLED (spectrum of activity)


Livestock Spray (Beef Cattle):

  • Horn Flies, Lice, including Tail Lice, and aids in control of Face Flies
  • Dilute in water: 1 gal. product in 75 gal.  or 5 oz. in 3 gal.
  • Dilute in water as indicated and spray directly on the animal only to the point of runoff. Use between 1/2 to 1 gallon of diluted spray solution per animal depending on size and hair coat. Do not treat more often than every 10 days. Do not apply to calves under six months of age. Brahman and Brahman-cross cattle should not be treated as they may show hypersensitivity to organophosphate pesticides. Do not apply in combination with other dermal organophosphate pesticides (e.g. trichlorofon). There is no withholding period from last application to slaughter.
  • Horn Flies, Lone Star Ticks
  • Dilute in water: 1 gal. product in 200 gal. or 2 oz. in 3 gal.
  • Apply as above. For severe tick infestations, dilution may be increased to 1 gallon in 50 gallons water.

Livestock Spray (Lactating Dairy Cattle):

  • Horn Flies, Lice, Lone Star Ticks, and aids in control of Face Flies
  • Dilute in water: 1 gal. product in 200 gal. or 2 oz. in 3 gal.
  • Dilute in water as indicated. Direct spray to cover thoroughly with up to 1/2 gallon of the dilution per animal. Repeat as necessary. Do not apply to calves under six months of age. No milk discard is required. Care should be taken that the spray does not come in direct contact with the lactating dairy cow’s teats unless they are washed with an approved cleansing solution and dried before milking. Apply the spray at least 20 minutes prior to milking or after milking has been completed.

Backrubber or Facerubber (Beef and Dairy Cattle):

  • Horn Flies and aids in control of Face Flies
  • Dilute: 1 gal. product in 25 gal. or 5 oz. in 1 gal.
  • Mix with any approved backrubber base oil reservoir of mechanical rubbing devices or pour one gallon per 20 linear feet on burlap or rope backrubbers. Keep backrubber or facerubber charged.

For further uses (poutry, kennels, etc.) read the product label.


  • LD50 (acute oral) in rats: 500 mg/kg (according to MSDS)
  • LD50 (acute dermal) in rabbits: >2000 mg/kg (according to MSDS)
  • Estimated hazard class according to the WHO: II, moderately hazardous.
  • RESTRICTED USE PESTICIDE in the USA: Due to acute oral, acute dermal, primary eye and primary dermal toxicity. For retail sale to and use only by Certified Applicators or persons under their direct supervision, and only for those uses covered by the Certified Applicator’s Certification.

Suspected poisoning? Read the article on dichlorvos = DDVP safety in this site.

Withholding periods (=withdrawal times) in days for meat & milk (country-specific differences may apply: read the product label)

  • Cattle Meat: USA NIL
  • Milk for human consumption: USA NIL

WARNING !!!: Never use on humans, dogs or cats.

Dichlorvos and all organophosphates (e.g. coumaphos, diazinon, dichlorvos, phosmet, etc.) etc. are highly toxic to birds, fish and aquatic invertebrates. Do not apply directly to water, or to areas where surface water is present or to intertidal areas below the mean high water mark. Do not contaminate water when disposing of equipment wash-waters or rinsate.

You may be interested in the following articles in this site dealing with the general safety of veterinary products:


Risk of resistance? YES. Resistance of houseflies and mosquitoes to organophosphates (incl. dichlorvos and tetrachlorvinphos) is widespread in the USA and worldwide, and can be very high. Cases of resistance of horn flies to organophosphates have been reported in the USA and elsewhere, but resistance of these flies to organophosphates is usually weaker and less widespread than to synthetic pyrethroids (e.g. permethrin).

This means that if this product does not achieve the expected efficacy against the mentioned parasites, it may be due to resistance and not to incorrect use, which is usually the most frequent cause of product failure.

Alternative chemical classes/active ingredients to prevent resistance of external parasites through product rotation:

These alternative products may not be available in all countries, or may not be available for spraying, or may not be effective against all the concerned parasites.

Learn more about resistance and how it develops.


Are the active ingredients of this product ORIGINAL* or GENERICS**?


*Meaning that they are still patent protected and generics are not yet available
**Meaning that they have lost patent protection and may be acquired from manufacturers of generic active ingredients other than the holder of the original patent.

COUNTRIES where this brand/product is marketed: USA
GENERIC BRANDS available? YES, but rather few with dichlorvos in the USA.

Click here to learn more about GENERIC vs. ORIGINAL drugs.

For an overview on the most used antiparasitic spray, dip & dust BRANDS click here.


RAVAC E.C. from BAYER(now ELANCO) is a broad-spectrum insecticide with generic dichlorvos and tetrachlovinphos marketed by BAYER in the USA.

Dichlorvos (also called DDVP) is a veteran broad-spectrum organophosphate introduced in the 1960s that has been abundantly used worldwide in agriculture, hygiene and veterinary insecticides. It has the specific feature of being highly volatile. This makes it particularly appropriate for misting or fogging because it easily reaches flying insects (mosquitoes, flies, etc) and penetrates into cracks and crevices where many pests use to hide (e.g. cockroaches, beetles, etc.). Its volatility also favors fast penetration into the insect's body, which results in a rather quick knock-down effect. However, when applied directly to cattle, it quickly evaporates and consequently its residual effect is rather weak, i.e. protection against re-infestation is rather short, not longer than 2-3 days.

Tetrachlorvinphos is another veteran organophosphate pesticide introduced in the 1960s. It has a broad-spectrum of efficacy against numerous insects. It has been poorly used in Animal Health but more in Crop Protection. However, as most organophosphates it has been vastly replaced by more modern pesticides in numerous countries in the last decades.

All organophosphates are veteran pesticides developed in the 1950s-1960s and are basically contact insecticides. This means that when the parasite comes in contact with it (e.g. during the blood meal, after landing on a treated host, etc), the active ingredient that impregnates the host's hair coat penetrates through the cuticle (i.e. the "skin" of insects and other arthropods) into its organism and disturbs essential biological processes in the parasite's body, in this case its nervous system.

Control of susceptible (i.e. non-resistant) horn flies is usually good with sprayed organophosphates, because they spend a lot of time on cattle and thus are exposed to the insecticide for a long period of time. Control of face flies is often not as good, due to their different behavior: they do not spend a lot of time on the animals and visit mainly body parts in the face that are humid with body fluids (eyes, nostrils, around the mouth), where the insecticide concentration is diluted by these body fluids. Stable flies and mosquitoes may bite the treated animal anywhere in its body and remain attached and thus exposed to the insecticide only during their blood meals that last a few seconds or minutes, which is often too short to kill them. Trying to control housefly populations with on-animal topical products is usually ineffective. The simple reason is that they spend most of their time off-the animals.

Nowadays this product is one of the few products containing organophosphates left for spraying animals against external parasites (flies, liceticks, etc.). Liquid concentrates containing organophosphates were widely used between their discovery (~1950s) and the 1990s. But subsequently most of them have been withdrawn and replaced by concentrates with less toxic synthetic pyrethroids (e.g. permethrin) or by more convenient ready-to-use pour-ons (mainly with macrocyclic lactones such as ivermectin, or synthetic pyrethroids). Against horn flies organophosphates (mainly diazinon) are still widely used in insecticide-impregnated ear-tags.

Insecticide concentrates for spraying or dipping such as this product often represent the cheapest option for insect control on animals. However the active ingredients used in such products are mostly rather old (introduced in the 1950s to 1970s) and many pests have developed resistance to them. More modern and more effective active ingredients for the control of external parasites are often not available as concentrates but only as ready-to-use pour-ons, injectables, or in the form of insecticide-impregnated ear-tags. They are usually more effective, more convenient and with a longer protection period than the concentrates, but are also more expensive and often not approved for the control of as many pests as the concentrates.

After administration to livestock or other animals, organophosphates do not have a systemic mode of action, i.e. they are not transmitted to the parasite through the blood or the host. Topically administered organophosphates are very poorly absorbed through the skin of the hosts, and what is absorbed is quickly broken down and/or excreted. Consequently the concentration reached in the blood is too low to kill blood-sucking parasites.

For best results it is very important to ensure a complete coverage of the animals' hair coat. This is best achieved after dipping the animals. Best alternative to dipping is high pressure spraying (depending on size and hair coat, adult cattle need 3 to up to 10 liters product for complete wetting). Efficacy after hand spraying or spot application are often poor due to the fact that using these methods some parts of the body may not be properly treated (e.g. inside the ears, below the tail, the udders, etc.), which allows a significant number of parasites to survive, reproduce and perpetuate the infestations. To learn more about spraying cattle and other livestock click here.


This article IS NOT A PRODUCT LABEL. It offers complementary information that may be useful to veterinary professionals and users that are not familiar with veterinary antiparasitics. 

Information offered in this article has been extracted from publications issued by manufacturers, government agencies (e.g. EMEA, FDA, USDA, etc.) or in the scientific literature. No guarantee is given on its accuracy, integrity, sufficiency, actuality and opportunity, and any liability is denied. Read the site's DISCLAIMER.

In case of doubt contact the manufacturer or a veterinary professional.