Rat Control

Rat Control

Since part of the disease cycle of rat/lungworm disease is in rats, it makes a lot of sense to keep rats under control.

I was recently at Home Depot and they have several types of traps: the traditional snap trap, electronic traps and the new Nooski trap. I’ve used snap type traps for many years, so I know that many times rats trip the trap and get away, sometimes maimed.  The trap can also make a bloody mess of rats that is unpleasant to clean up. I agree with Nooski that the catch rate is about 25% or so on these types of traps.

So I purchased the Nooski trap and a Victor Electronic rat trap with the idea that I would put them side by side and compare results. I had both traps for about a month before I caught my first rat, simply because there were no rats around. This is a normal pattern for me because I would kill a rat or two, then it would take some time for new rats to move in. Also, I find that rats tend to move into the house during periods of heavy rain.

Victor electronic rat trap
Victor electronic rat trap

The Victor Electronic Rat Trap Review

This trap was interesting to me because I am in the electric fencing business, and this trap similarly uses electricity to dispose of rats.  The trap was $40, and it uses 4  C batteries. It took a whole month before I caught my first rat in it. During that first month, instead of rats, I caught one gecko, and dozens of cockroaches. I also found ants and slugs inside the trap eating the bait which are unpleasant to clean out of the trap. The cockroaches would trigger the kill alarm on the unit until I came to reset it, during which time it would not be able to kill a rat if one came along. I used up one set of 4 batteries catching all those cockroaches and not one rat.

This trap is a bit tricky to set as I found out from using it, and the instructions don’t tell you this. When you turn on the trap, there is a 30 second pause, and then you hear a soft buzzing noise for about 5 seconds or so. Then the trap is set and working properly.

This trap is constructed with three metal plates on the bottom for the rat to contact, with positive and negative polarities. When a rat stands on 2 different plates of 2 different polarities, the rat gets a lethal shock.  Between the three plates is a plastic strip that insulates between the metal plates.

The problem is, however, that if there is anything such as water or bait residue on the plastic between the plates, the initial buzzing sound will keep going, indicating to me that the trap is being shorted out and that my batteries will get drained. So when this happens, I have to reach inside the trap with a paper towel and clean between the plates, and then turn on the trap and see if it’s working properly. Sometimes I’ve had to do this as many as 5 times to get it clean and working because it’s hard to get your hand in there an get to the corners. The inside of the trap gets dirty from the bait if you don’t clean it everyday too.

I’ve also determined that rats are able to steal the bait from this trap and get away and either not get a shock for some reason or maybe get a partial shock and get away, I don’t know for sure. What I do know is that the bait was missing and I actually saw a rat a few minutes later. My bait was stolen at least 3 times from this trap.

As for keeping this trap clean, I find that the bait I use (bananas) seems to corrode the metal plates and makes a mess so you have to clean the inside regularly which is tough to do because the trap doesn’t open from the top. Also, if you do catch a rat, when an animal dies, it loses fecal and urinary control, so it can make a stinky mess inside the trap.

Nooski rat trap
How the Nooski rat trap works

The Nooski rat trap review

No more poison, no more glue boards, no more snap traps. The NOOSKI revolutionary ring trap is an innovative leap in design, with significant benefits over other devices.

Attracted by lure, the rodent enters the trap thus releasing a powerful rubber latex ring onto the neck/chest area. The rodent is expelled from the trap being crushed by the ring and dies instantly next to the trap without much suffering.

The instructions say to fasten the trap to the floor, but I can see that many people with nice floors may not want to do this. (A video on the Nooski website shows that it is not essential to attach it to the floor, that’s only to prevent pets from moving it.)  I fastened my trap to a piece of PVC board to give it stability, and the PVC won’t rust or rot so I can easily wash the trap and keep it clean which is an advantage over the electronic trap. I never found ants or slugs or geckos in this trap eating the bait.

Here’s a very good video showing the Nooski in action. (View with caution though as it has a segment in the middle showing the rings used for goat castration.)

I also contacted the Nooski people and asked them about the purpose of the long plastic tube on the trap because during the month before I caught my first rat, I imagined that a rat might get claustrophobic crawling into that tube. This is what they had to say about it: “The black tube we refer to as the safety tunnel, is designed to keep companion pets safe (cats and dogs). Our field trials have shown no evidence that the catch rate is any greater with a shortened or no safety tunnel. Rats are not afraid to travel up narrow tubes, they have been known to climb several stories in a 2 inch drain pipe.”

Here’s the Nooski website: http://www.nooski.com/

As I said earlier, it took a month after purchasing this trap until rats moved in, but  when they did,  I caught 3 rats for 3 nights in a row with the Nooski trap. It works as advertised. The rat is found outside the trap where it is easily scooped up with a dust pan.  There is no bloody mess to clean up.  To clean, take the trap apart and wash it with a hose, or even put it in the dishwasher since is is made of tough ABS plastic.

The trap sells for $20 at Home depot and they also have refill rings reasonably priced at a pack of 20 rings for $3.75 compared to online retailers at $15-$20. Packages of 100 castration rings (which are the same thing) sell for $5.32 on up on Amazon and Ebay with free shipping making replacements very affordable. The rings are even more affordable at Del’s farm supply in Hilo.  A package of 100 castration rings, (which are identical to the rings that come with the Nooski) sell for $3.99. Miranda’s feed store in Hilo told me on the phone that they had 100 castration rings for $1.99, but then next day when I went in there they told me they were out and don’t know exactly when they will get more in.

And lastly, on the humorous side, remember that Nooskis don’t catch rats – rather, a Nooski catches a Ratski.

thumbs up for Nooski rat trap
The Nooski rat trap gets a thumbs up review

The Score – How they compare – Nooski vs. Electronic trap

So so far my number of rats caught is:  Nooski – 3, Victor Electronic trap – 1

Misses: Nooski – 0, Victor Electronic trap – 3

I don’t use the snap type traps anymore – too many misses, and misses make rats wary of the traps and harder to catch. It is better to catch them the first and once in the Nooski.

Update 5/21/17: It’s been 10 weeks since I last caught a rat, which is good news because there have been no rats around,  but last night I caught 2 rats hours apart in my modified Nooski trap. That’s right, I modified the trap by cutting off the safety tunnel because I have no pets to keep safe and I thought the trap would work better because the bait is closer to the entrance so the smell of the banana bait would be picked up by a passing rat easier.

Well, I was right, and the modified trap works great, catching two rats in one night. The picture below shows where I cut it because you want to not cut too close to the slot that keeps the trigger mechanism from swinging too far, into the rat’s path and getting broken.  See pic below:

modified nooski rat trap
The modified Nooski Rat Trap

The photo shows an un-modified trap and one that has been cut. The white arrow shows how I preserved the slot. I know, the manufacturer said not to do this because a rat has no trouble climbing through a tube, but I did it anyway and it works. And I should add to notice in the photo that the modified trap needs to be secured to a board whereas an unmodified trap does not. The reason is because of the short length of the modified trap,  I thought the trap might slide away from a rat going into it. By being on a board, the rat’s feet will have firmness to enter the trap and not push the trap away.

I also stopped using the electronic trap because I’d rather buy 100 Nooski rings for $3. than keep buying 4 C batteries.

About rats in Hawaii

There are 3 types of rats in Hawaii:

  • Polynesian rat or Pacific rat (Rattus exulans) is comparatively small in size (4-5 inches long) and weighs 2-3 ounces. This species is a field rat and rarely found near buildings in Hawai`i.
  • Black or roof rat (Rattus rattus) is a medium to large rat (5-7 inches long),  is an expert climber and wire scaler, t is found in agricultural areas, wooded gulches, kiawe forests, and both wet and dry forests. The black rat has now displaced the Norway rat as the most common rat found close to human habitations and especially in wet areas such as streambeds, drainage canals, and sewers.
  • Norway rat, also known as the cellar rat, brown rat, wharf rat and sewer rat (Rattus norvegicus) is the largest of the rats found in Hawai`i (8-10 inches long) and weighs 10 to 18 ounces. The Norway rat is a species that burrows in the ground, rubbish piles, garbage dumps and under walks and docks.  Likely originating in China, the largest specimens can top 2.2lbs.

Some facts about rats:

  • Rats can climb brick walls, trees, and telephone poles, and walk across telephone lines.
  • Rats can fall from a height of 50 feet without getting hurt.
  • Rats can jump three feet in the air from a flat surface and leap more than four feet horizontally.
  • Rats can scamper through openings as small as a quarter. General rule: If a rat’s head fits into the hole then the body will follow.
  • Rats can chew through plastic (like plastic bottles causing them to leak), lead, cinder block, and aluminum sheeting. Rats’ teeth grow about four inches a year, and they have to gnaw on things to keep their teeth from pushing through their skulls.
  • Rats are prolific. Mother rats can have as many as 8-12 offspring about every 30 days as long as there is enough food, shelter, and water. The young rat is sexually mature at 3-4 months of age.
  • Rats are nocturnal (active at night), so when you see rats during the day this may signify a rat population out of control, or you may be seeing weaker, less competitive rats that are forced out into the daylight by stronger more dominant rats.
  • Rats cause great damage to agricultural crops such as sugarcane, macadamia nuts, pineapple, coconuts, coffee, and other fruit and vegetable crops.
  • Polynesian rats first arrived in Hawai`i with the Polynesians (approx. 400A.D.) and black and Norway rats arrived with Westerners in the 1780s.
  • Rats cannot go without food for more than 4 days.
  • Rats do not like the smell of other dead rats. The good thing about the Nooski trap is that the rat is ejected and dies away from the trap.
  • Rats may also avoid traps because of the human scent. It may help to wear gloves when handling a trap to avoid this, but I have not had a problem by not wearing gloves.
  • The biggest, feistiest sewer rats can send your average house cat running for the hills.
  • A rat can go longer without water than a camel.
  • Rats can climb up the insides of pipes with diameters as
    small as one and one half inches (four centimeters).
  • Did you know that contrary to popular belief, rats prefer fresh, high-quality foods and will reject spoiled or inferior food items when given a choice? Desley Whisson, Extension Vertebrate Pest Specialist, University of California  claims: Rodent baits should be made from high-quality food materials, and baits which have become rancid or insect-infested should be discarded.
  • Rats usually stick together in groups called packs. New packs are formed when a male and female go off on their own and nest in an area that doesn’t already contain a pack. Brown rats are usually led by the largest male in the pack. Other rats may have several dominant males or females in a pack.

Disadvantages to common rat control methods

  • Rat poisons can be eaten by pets such as dogs and cats making them very sick or killing them too. Rats that ingest poisons can be eaten by other animals such as owls, killing them too.
  • Glue traps can take several days to kill rats causing an agonizing death.

Natural Rat Predators in Hawaii

The mongoose is a natural rat predator, unfortunately those who introduced them to Hawaii made one big oversight: the mongoose is diurnal, and the rat is nocturnal. I throw my dead rats outside in the daytime and the mongoose take them away rather quickly.

Barn owls are found on the Big Island and can eat 3 to 6 rats each night. That’s 1,095 to 2190 rats per year for each owl.