ContraPest Frequently Asked Questions

Below are some frequently asked questions about ContraPest from our customers.  If you have a question that you do not see here, please feel free to reach out to our Technical Services department at 928-482-7312 and we are happy to help!

What is ContraPest bait and how does it work?

ContraPest is a liquid contraceptive bait that reduces fertility in both male and female Norway and roof rats. In females, ContraPest interferes with ovarian function so that there are few to no ovulations and in male rats, it inhibits the production and maturation of sperm.

What are the advantages of ContraPest?


What are the active ingredients in ContraPest?

The actives include:
a) 4-Vinylcyclohexene diepoxide (0.09604%)
b) Triptolide (0.00118%)

How quickly does ContraPest work and for how long?

Once ContraPest is available to rats, fertility is reduced within 24hrs. ContraPest provides a cumulative effect, thus the more the rat consumes, the greater the result. ContraPest is a contraceptive, not a sterilant, so a continuous supply maintains reduced populations.

How does ContraPest metabolize in rats?

There are two active ingredients in ContraPest, 4-vinylcyclohexene diepoxide (VCD) and triptolide.

VCD when exposed to water, readily and rapidly hydrolyzed primarily into inactive monoepoxides. Liver enzymes reduce these epoxide groups to hydroxyl groups, which along with other inactive metabolites are excreted in urine and feces. VCD has a half-life in rats of 15-20 minutes.

Triptolide also rapidly metabolizes into inactive compounds that are primarily conjugated with glutathione, GSH. The half-life of triptolide in a rat is 20 minutes, similar to VCD.

To summarize neither VCD nor triptolide accumulate in rat tissues. Liver enzymes rapidly breakdown both VCD and triptolide into inactive metabolites that are excreted primarily in feces and urine.

Where can ContraPest be used?

ContraPest can be used in a variety of settings. Please read and follow label instructions for deployment. It is registered for indoor, non-food use and within 1 foot around external perimeters of transit systems, public and private buildings, commercial residential structures, and/or other man-made structures. Do not place bait stations where they are likely to become submerged or inundated with water, or on an uneven surface. To avoid damage to the bait station, do not use bait stations in areas open to hooved livestock or potentially destructive wildlife.

Do I need to pre-bait when using ContraPest?

Pre-baiting is not required, but for the best results, we highly recommend pre-baiting with SenesTech Control bait, which is similar to ContraPest but does not contain the active ingredients. SenesTech Control bait is a cost-effective tool to help identify foraging locations and can help rats acclimate to stations before the active product is deployed. This is especially helpful at sites where a heavy baiting campaign was recently initiated, and rats may be showing signs of bait aversion or bait shyness.

Are there baiting protocols when applying ContraPest?

Our studies have shown that ContraPest is most effective when placed at foraging locations. Given this, bait station spacing can be a more targeted approach to maximize consumption and save costs.

When identifying foraging locations, the focus is on where rats actively feed. It is important to note that areas with high rodent activity (burrows, runs, rub marks, droppings, etc.) may not necessarily correspond to areas where rats will be comfortable going into a station to feed. If you are new to a site, non-toxic blocks and chew cards can be used to identify rat forging areas. We have also created a control bait that can help confirm foraging locations prior to deploying ContraPest.

Who do I call If I have deployment questions?

You can contact the Technical Services department for more information
Phone: 928-482-7312

When should I change the bait and how often does the bait station need to be serviced?

Please read and follow label instructions for ContraPest. ContraPest must be replaced every 30 days.

After initial deployment, frequent servicing of the stations, biweekly if possible, may be helpful until steady consumption begins to monitor uptake and confirm adequate station placement. If tanks are empty, replace tanks prior to 30 days.

What are the effects of ContraPest on non-target animals (pets, birds, raptors, other animals, etc.)?

The delivery system of ContraPest is designed to minimize handler exposure and is dispensed inside tamper-resistant bait stations, minimizing the risks to non-target species.

ContraPest is a reversible contraceptive and the active ingredients metabolize to inactive within 15 minutes, minimizing risk to predatory animals. ContraPest does not alter rat behavior or make them more vulnerable to predation, therefore reducing the chances of secondary exposure.

Does ContraPest work on mice or other rats?

ContraPest is registered for use on Norway and roof rat species only.

What is the shelf life of ContraPest®?

In the initial submission for EPA registration, the shelf life component was waved/deferred, with the understanding that this information would be provided at a later date. However, we are currently working on providing the EPA with data and documentation to calculate shelf life as part of our continuous label improvement efforts.

I heard that the EPA approved a new label that removes the RESTRICTED USE PESTICIDE designation from ContraPest®. If so, why is the RUP disclaimer still listed on your website and sales materials?

While we are very pleased to have EPA approval of a new label that removes the RESTRICTED USE PESTICIDE designation from ContraPest®, we are also in the next step of individual state approvals. During this process, we will continue to utilize our current label in all states that have not yet approved the new label, and thus our RUP disclaimer will also remain on our communications, including our website and sales materials. We will make appropriate updates as the state approval process is completed.