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Availability:
In Stock.
Arrives
Tuesday, Oct 20
Features
- CONVENIENT PEST CONTROL: Protection against a wide range of residential and commercial pests populations including spiders, scorpions, fleas and mosquitoes.
- QUICK KILL: Onslaught FastCap Spider and Scorpion Insecticide offers a convenient and approach to pest control.
- INDOOR AND OUTDOOR APPLICATIONS: Effective pest control in and around livestock facilities, on turf, ornamentals, landscapes, and in food and non-food areas of commercial and residential structures.
- ACTIVE INGREDIENTS: Combines esfenvalerate and prallethrin with synergist piperonyl butoxide (PBO) for fast-acting pest control.
- A LEGACY YOU CAN TRUST: Driven by expertise and industry commitment, MGK has been developing pest control products based primarily on botanical and innovative technologies since 1902.
Description
MGK 10085 Onslaught FastCap Spider and Scorpion Insecticide, Off-White
Item Form: Spray
Item Weight: 1.2 pounds
Liquid Volume: 1 pints
Active Ingredients: Esfenvalerate,Prallethrin,Piperonyl Butoxide
Brand: MGK
Brand: MGK
Unit Count: 16 Fluid Ounces
UPC: 848920000492
Included Components: Insecticide
Item Type Name: Spider and Scorpion Insecticide
Manufacturer: MGK
Model Number: 10085
Part Number: 2964-D05
Item Form: Spray
Target Species: Insects
Item Weight: 1.2 pounds
Liquid Volume: 1 pints
Active Ingredients: Esfenvalerate,Prallethrin,Piperonyl Butoxide
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Tuesday, Oct 20
Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
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Top Amazon Reviews
Style: Scorpion Insecticide
Don’t know what’s different about this year than all the others, but the scorpions are out with a vengeance. It’s seriously not fun. We’ve had them in our bed, in the dog beds, in the bathrooms, in the kitchen, in bedrooms, in the living room, on the ceiling, and the list goes on and on. Truly awful, and it was showing no signs of relief. We had been using Wondercide indoor pest control cedar scent spray, which did help, but didn’t solve. It smells great, which is a bonus, and is totally safe for us and our pets, which we love. But again, it didn’t eradicate the scorpions from our home. We tried the traps. Again, they work and serve their purpose, but they don’t stop the scorpions from entering, they only help catch them once they’re in. So problem still not solved. We’ve also tried other things: cedar wood blocks and chips everywhere, peppermint and other heavily scented scorpion deterrents, etc. No dice. We really tried to stay away from insecticide, because of how many animals we have, but we were at the very end of our rope. There aren’t many options when it comes to options that can kill scorpions. So this what we went with. We followed the directions and sprayed outside the night we received it. When we woke up the next day, it was like a graveyard out there. Dead bugs everywhere. Not just scorpions, but stick bugs, beetles, stink bugs, June bugs, a variety of spiders (including tarantulas!), mosquitos, crickets, and other things I couldn’t even begin to tell you what they were. Since then, we’ve also sprayed inside, and have found three dead scorpions, three dying scorpions, several new dead scorpions in the traps, and now, about a week in, no scorpions for two days in the house! One I found the first day that was still kicking, I grabbed him with my tweezers and put him in a bowl, then sprayed him. I watched him squirm for about 15 seconds, before he flipped over on his back and died. Just like that. Just stopped, flopped, dead. Also, we run a dog rescue here, and we have 19 dogs. During the day, the dogs are mostly outside in the yard and/or in their outdoor kennels. Since spot spraying and spraying the trees outside, there is a dramatic decrease in the amount of flying insects. >90% decrease in flies, mosquitos, moths, and June bugs. Amazing! So far, no ill effects on us, the dogs, the reptiles (snakes), amphibians (frogs), or small critters outside (bunnies) at all. No impact on the landscaping, no residue or discoloration left on the carpet, walls, or floors. No smell, except maybe a very faint buttery smell when it’s very first sprayed. It’s easy to mix, since the container has the built in measure, and you only need .5-1 ounce per gallon. That’s 16-32 gallons with this 16oz bottle. That’s a great deal for so much peace of mind! This stuff works. It’s safe and easy. Just follow the directions. Don’t over mix it (no need to waste it), make sure to let it dry completely before people or pets touch it, and you’ll be all set.
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Reviewed in the United States on June 20, 2024 by Nicole S.
Style: Scorpion Insecticide
I've been extremely frustrated with my current pest control company and definitely am overpaying for it. Decided to finally cut the service and do my own pest control with MGK Onslaught fastcap. My main issue has been spiders, especially on my privacy fence. I followed the instructions and sprayed this on the fence and outside of my house 1 month ago and boom. No more spiders. And no more ants. And no more other bugs. I mean this thing works like magic. No downside, just make sure you mix 1oz of the Fastcap with 1 gallon of water in a sprayer and get to work. Much cheaper than commercial pest control and dare I say, works better too.
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Reviewed in the United States on October 14, 2026 by K. Ferguson
Style: Scorpion Insecticide
This stuff is great! I live in Henderson, NV and was starting to see a lot of scorpion activity in the backyard plus found a couple in the house. I also had large red ants, crickets, spiders, and roaches throughout my backyard which is about 1/3 acre. I was using Pestie for the house boarder and supplementing with Syngenta Demon WP in various spots in the backyard. The combination worked okay, but not good enough. I have artificial grass in the backyard and at night, my dog's poop would be covered by crickets and roaches (gross!). All those bugs are essentially food for scorpions. So I cancelled my Pestie subscription and tried MGK Onslaught FastCap instead. It mixes 1 oz per gallon for scorpions, so I used 1 oz for the perimeter of the house (3 ft up the wall and 4 feet on the ground), then I mixed another 3 gallons and sprayed all along the property perimeter, retaining block, river rock, and anywhere else the scorpions would hide. I also sprayed the entire artificial turf area. Basically, 4 oz covered my entire 1/3 acre. The effect was AMAZING! That night, there were no crickets chriping at all. The biggest tell was my dog's poop which had not one single roach or cricket. Ants were all gone and no roaches in sight! For the scorpions, the effect wasn't as immediate. I still found a few scorpions the first few nights, but then about 4 days or so later, the scorpions I did find were actually dead! I've never seen that before. Usually, the activity just dies down, but to actually see dead scorpions made me happy. That means even if they did get into the house, they'd eventually die anyway. I placed a few sticky traps along the baseboard of the house near the entrance doors and they are all still clear. It's been about a month since I sprayed and it's still holding up. We had a few days of rain recently and I now can hear a couple crickets in the backyard again and I've seen a couple large red ant scouts wandering about, but any poop on the grass is clear of bugs. It sounds gross, but that's my measure of effectiveness. This stuff is supposed to be pet safe after it dries and as far as I can tell, it is. I have a 70 lb dog and she rolls around in the grass daily with no issues. This will definitely be my go to pesticide from now on. A couple other points to note is there was no odor when spraying unlike the Syngenta which had a strong pesticide smell. It mixes very easily and it's easy to measure with the built-in dosing chamber.
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Reviewed in the United States on October 7, 2026 by Neutronmx
Style: Scorpion Insecticide
My son has used this product for years, and he said it is very effective for using for spiders and scorpions in the home. I have canceled my pest control contract, and he is now treating my home with this very easy to use the product. The concentration is good, so there is no huge container to store between treatments.
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Reviewed in the United States on October 13, 2026 by S Scurlock
Style: Scorpion Insecticide
I bought my first bottle 5/7/2025. I moved to the country side and June starts scorpion season. I have a dog and 2 toddlers. This product works! When I bought this, they did not have the option for prime, so I did have to wait for the product to come in. I’m glad that it has changed since then as I have been out of the product for 3 months now (since June 2026). I honestly chose this brand of all the brands available because of childhood commercials! I recognized the brand and went with it. It does EXACTLY what it’s meant to do! I’m a DIY and save some money kind of girl, so I always try to do my research on the best products or whatever I feel has more rewards than risks. I recommend that if you have a sensitivity to chemicals or have asthma, then I suggest that during treatment you wear a mask, long sleeves, and gloves to keep yourself protected and make sure that if you have kids or pet pets, that you make sure that the product is completely dry and there’s a well ventilated space before having them come back in the house, because it will trigger a reaction. By reaction, I mean, coughing, sneezing, and that could be in both people and animals. Once it is completely dried, you won’t have that issue. Also, once you get to the end of the bottle, if you don’t have enough, just know if you try to use every last bit like I did because you wanna get your moneys worth it will not be as effective as the product to water ratio will not be the same. I hope this helps and I’m off to buy another bottle.
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Reviewed in the United States on September 19, 2026 by Oleta Crofoot-Harris
Style: Scorpion Insecticide
Worked fantastic for my scorpion and nuisance spider problems.
Reviewed in the United States on June 4, 2026 by Chris B.
Style: Scorpion Insecticide
Scorpion season started earlier this year in South Texas. Ordered this after reading reviews for multiple days and feeling confident that it will help us. Morning started with us finding a scorpion in the laundry room. We caught it in a glass and sprayed one part of the floor with Harris scorpion killer and the other part with Fastcap scorpion killer and waited for both sides to dry. Sat the scorpion on the Harris side and turned the vase over it so it can be controlled on the treated area. Let it run around for about 30 seconds (seemed a reasonable time for it to naturally cross over) and scooped it back into the vase. Watched it for about 2 hrs happily crawling around the vase. No lameness no twitching. Just alive. Time for the second test. This time sat it on the fastcap treated area and again let it run around for 30 seconds. Scooped up and watched it. Here is what happened after exposure: After 2 minutes he got really really slow and we saw right away something is effecting him. After 5 minutes he started acting like a drunk. Uncontrolled body moving, legs kinda tried to crawl in the air and the tail bent over its body. After 10 minutes he flipped on his back and started twitching like crazy. Then nothing. Legs curled up, tail went straight and no movement at all. I moved the lifeless body around in the vase to test any reaction- NOTHING! Watched him for the next 3 hrs. Checked about all 20-40 minutes. At the beginning there was still some slight movement in the legs and pinchers here and there but you could definitely tell it’s just muscle spasms. After 3 hrs I disposed of a dead scorpion. To be fair, he was first exposed to Harris but lived on. Not saying that didn’t somehow affect him but after exposure to fastcap it went very quick. After that I sprayed my entire inside of the house. Under the sinks, behind washer/dryer and along all perimeter of the inside. It’s raining but as soon as the rain will stop I will spray generously outside up the siding and along the base and grass surrounding about 2 feet of the house. My goal is to knock em out the way I saw it happen today before they even get the chance to find an entry point. I’ll probably repeat my experiment with fastcap in about a week to see how the stuff works after some time and will update my review then. For now all I can say is I am happy seeing first hand that it kills these crustaceans fast and am looking forward to report the effectiveness in a couple of days regarding the left over strength HOPEFULLY less scorpion sightings. Before any treatment we found 6 within 7 days.
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Reviewed in the United States on May 5, 2025 by Jason McCulloch
Style: Scorpion Insecticide
Living in Phoenix, scorpions are an ever present threat. Having been let down by "professional" pest control and their bad reputation for watering down their product, I decided to to it myself. Been using this product for years, and very happy with the results. Around here, it's not IF you'll encounter scorpions, it's WHEN. I use this to spray interior AND exterior.
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Reviewed in the United States on August 22, 2026 by Jeff A.