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Keeping & Breeding Crickets As Feeder Insects by Renier Delport

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Keeping & Breeding Crickets As Feeder Insects by Renier Delport


Feeder Rats & Mice



Feeder Rats & Mice

| Introduction | Classification | Biology | Stages | Sexing | Supermice | Handling | Keeping & Breeding | Breeding | Food Related Problems | Behaviour | Feeding To Other Animals - Ethics | Environment Enrichment | Potential Health Problems | Books | Related Topics | References |

Feeder Rat & Mouse Introduction:

The domestication of rats (Ratttus rattus) and mice (Mus musculus) began well over a century ago when these rodents were seen as the major spreaders of various unpleasant diseases. So called "rat-catchers" were employed to get rid of these pests, as they were called then. Rat-catchers began to keep and display different colour varieties in public houses. Although all rats and mice descended from their original brown ancestor (Rattus norvegicus), today's domesticated rats and mice are far removed from their wild relatives, and are unlikely to present any significant health risks to their keepers.

Please note that this section is for Feeder Rats & Mice, for the section on Pet Rats & Mice click here.

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Rat & Mouse Classification:


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Rat & Mouse Biology:

The Class Mammalia (mah-ma'le-ah) consists out of a diverse group of animals, which all poses hair, mammary glands, specialized teeth, a diaphragm, three-middle-ear ossicles, sweat, sebaceous and scent glands, a four chambered heart and a large cerebral cortex. The Infraclass Eutheria (u-ther'-e-ah) includes all the mammals with complex plancentas or the "placentals". Rodents are the largest order of mammals, and have single pairs of ever-growing incisors. It is important to note that rabbits do not belong to this order, but to the Order Lagamorpha.

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Rat & Mouse Stages:

Rats and mice are divided into four stages according to their age and size. These stages are pinkies, fuzzies, hoppers or jumpers and adults. Pinkies or pinks (day 1 to about day 7) are new-born rats and mice that are still hairless. Fuzzies (day 7 to about day 21) are in their fuzzy hair stage until they open their eyes. Hoppers or jumpers (about 3 weeks) are weaned offspring. In every stage males (bucks) are usually a bit larger than the females (does).
    Rats are significantly larger than mice. The average rat is about 25 cm / 10 " with the average mouse about 15 cm / 6 " (incl. tail). Mouse babies are called pups and rat babies are called kittns.

a Pregnant Mouse Picture b Female Mouse With Pups c Female Mouse With Fuzzies
d Mouse Picture    

 Figure 1  The different stages of mice. a Adult doe in late pregnancy; b Adult doe with pups; c Adult doe with fuzzies; d Adult buck with hoppers.

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Sexing Rats & Mice:

To know what to look for, classify the animals to be sexed into one of the following groups:

  • before three weeks of age
  • after three weeks of age, but before sexual maturity
  • after sexual maturity

Sexual maturity or puberty is where the animals are ready to mate and conceive viable offspring. This is usually about six weeks after birth.

Before three weeks of age
The best time to sex in this group is about two to three weeks after birth. This is at about the end of the fuzzy stage, just before to just after they've opened their eyes. Females will display nipples on their ventral side through their fur and males won't have any nipples. When examining animals to late in this group the fur will have grown over the nipples, making it easy to confuse females for males.

After three weeks of age, but before sexual maturity
At this point males and females appear almost identical. As mentioned above, no nipples will be visible on female animals at this stage and males have not yet developed prominent external genitalia (a penis and two testicles). Sexes can be identified by comparing sexes with each other. Both sexes will appear to have a penis, but males will have a greater distance between the penis (the real penis) and the anus (situated just ventral to the tail). To make adequate space for the testicles, this space will be about double the distance than in females. In females it is not a penis but an external urethral opening through which urine is excreted.

After sexual maturity
After sexual maturity both sexes have fully developed external genitalia. Males have visible testicles with a distinct penis, and females have a pink vulvar opening without testicles ventral to the anus. The vulva becomes more pink to reddish when the animal is in oestrus (the time when ovulation of the ovum takes place).

a Adult Male Rat (Rattus rattus) External Genitalia Picture b Adult Female Mouse (Mus musculus) External Genitalia Picture c Adult Male Mouse (Mus musculus) External Genitalia Picture

 Figure 2  The external genitalia of rats & mice. a Adult male rat (buck). Note the penis & the large visible testicles; b Adult female mouse (doe). Note the similarity between the external urethral opening & the penis in bucks. The distance between the anus, situated just ventral to the tail, & the urethral opening is significantly smaller than those in bucks. Teats might also be slightly visible in light coloured fur; c Adult male mouse - note the penis & the visible testicles.

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Supermice are apparently the hybrid cross between rats and mice. They are bigger than mice, but slightly smaller than rats. Their young (I assume pups), are born with fine long hair covering parts of their bodies. Their main advantage other then their size is the fact that their excreta do not stink and their cages can go without cleaning for months.

A B Supermice Pups

 Figure 3  Supermice. A Supermouse adult; B Supermouse pups. They are born with long fine hair covering parts of their bodies.

Rat & Mouse Handling:

It is easy to pick up and handle larger rats, but mice are a lot smaller and can easily be hurt. Don't ever handle wild rodents without protective hand gear. Rats and mice can be picked up by their tails. Try to grip the tail as near the base as possible and support the body of the animal with the other hand by letting it stand on your palm. It is not always necessary to constrain tame rodents, but if it is a bit edgy or it might fall or jump while holding it, keep hold of its tail. Never hold rodents around their bodies and never let small irresponsible children hold rodents. Don't handle more than one rodent at a time as they might be too much to handle. Always keep your hand in front of a tame rat or mouse for a before picking it up so that it can become familiar with your smell.

Rodents can get tame enough for you to let them walk all over you and even to let them climb into your clothes (it you are comfortable with that). Remember that even tame animals must be handled with caution. Never put a tame rat or mouse on the ground without keeping a close eye. Tame rats and mice will happily sit on your shoulder, in an open pocket or underneath loose clothing if you let them.

If any rodent bites you and draws some blood it is recommended to see a doctor immediately for a rabies and/or a tettanus vaccination. Wild rodents can be picked up by their tails to prevent them from biting. Make sure that the animal can't grab your hands or shake it off when it gets hold of its own tail to pull itself up.

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Keeping & Breeding Rats & Mice:

The following must be taken in consideration before keeping and breeding rats & mice:

These animals and their cages can smell bad very easily. Males tend to stink more than females. The only way to overcome this stinking problem and prevent discomforts and diseases is to clean the cages once to three times a week (depending on the number of animals per cage and on the type and size of the cage) and by not overcrowding them in small cages.

To keep and breed rats and mice you will need the following basics:

  • a cage, cages or a large type of container
  • space
  • food & water
  • bedding
  • a shallow container for food
  • a shallow container for water
  • keeping and/or breeding stock

Cages & Containers

Do not try to keep rats and/or mice and/or hamsters together in the same container. They will fight and can and most probably will kill each other!

For rats you will obviously need larger cages than for mice. The size of the cage also depends on the number of rats or mice you want to keep per cage. The more crowded the cage is, the faster it will start to smell bad. As a rough rule, don't keep more than four mice in a confined space of 35 x 25 x 13 cm / 14 x 10 x 5 ".

Any secure container can be used to house your stock. Old glass or fish tanks with ventilated lids are ideal for rat & mouse keeping. Large or small "Pal Pens™", any hamster or mouse mesh cage, self made containers or anything large enough which is escape proof. Do not use shoe boxes, thin wooden cages or anything similar, sooner or later they will literally eat their way out of it! Note that the openings in some mesh cages are big enough for mouse hoppers to escape. Chewed holes or openings should be properly closed as fast as possible, no matter how small it might be.

Cages and containers need as much ventilation as possible. Proper ventilation decreases the build-up of urine which will lead to excessive bacterial contamination and respiratory problems. Inadequate ventilation is unfortunately the only problem with glass tanks.

When constructing cages or containers it is important to take cleaning methods into consideration. Cages and containers will have to be washed and sometimes disinfected on at least a weekly basis.

Rats and mice are both nocturnal (night living) animals. The darker you can make their surroundings when not attending to them, the better. A towel or blanket can be placed over the cage or container, but don't try this with mesh cages as the animals might start to eat holes in the fabric. Don't put cages or containers in direct sunlight, not even in front of an open window. Apart from the fact that sunlight might increase the temperature to lethal proportions, rats and mice don't like sunlight and might feel threatened by it. See through plastic or glass, aquarium type containers will heat up very quickly (even if it is well ventilated) and can cause cruel mortalities.

a b c d
e f Mouse Cage Bottom g h Mouse Cage Bottom Fixed With Pratly Putty (Tm)

 Figure 4  Different types of housing for rats & mice. a & b Smaller & larger acrylic containers, also called Dessert dens or Pal pens™; c Glass aquarium with a lid; d Hamster mesh cage; e Mouse mesh cages (35 x 25x 13 cm / 14 x 10 x5 ") are ideal for commercial mouse breeding; f Mouse mesh cage plastic bottom; g Self made container with a mesh roof & a modification for a waterer; h Mouse mesh cage bottom fixed with Pratly Putty™.

Large single bird cages are ideal for one or two rats and larger 3 foot fish tanks can be used to house a few rats. Rats should preferably be given large cages with extra climbing space. Large bird cages with ladders and ropes are more preferable than closed smaller containers. Walk-in or outside mesh bird cages decorated with ladders, logs and rocks makes interesting housing for a whole lot of rats. Outside cages should be situated next to a wall so that there is adequate shade during the day. The wiring should be gap free and the floor should preferably be cemented to prevent rats from digging holes and dig their way out. Although these cages are usually outside it is still important to clean it out regularly.

Cage Maintenance
Pratly Putty can be used to fill chewed holes in plastic bottoms of commercial hamster and mouse cages (Fig. 3). Mesh cages should also be sprayed with a non-toxic spray paint on a two-yearly or when-needed basis to prevent the wire from rusting and animal toxicities.

Room temperatures (24 ºC / 75 ºF) are warm enough for most rodents. Some genetic strains might have different temperature requirements. Laboratory rat and mouse strains usually need constant day and night temperatures throughout the year. Abrupt and large temperature fluctuations will induce stress, reduced growth, poor reproduction and may ultimately lead to increased mortalities. During cold winters or cold spells, especially when only shredded paper is used as substrate (not recommended), it is important to provide external heat. Heat pads or heat strips bought from most pet shops can be placed under, on the outside, of containers. This type of heating should never cover more than about a third of the floor area of the cage or container. Standard heating equipment such as heaters, heating fans or heated air conditioning can also be used. Make sure there is enough ventilation and ad lib water when using any external heating sources.

It important to make sure these animals are always supplied with constant or ad lib food during cold weather. It is important to make sure these animals are always supplied with constant or ad lib food during cold weather. Wet and cold environments might be enough to starve a small rodent to death within one night.

Food & Water
As with any animal, fresh water and the correct food should be available on a constant basis (ad libitum). Water dishes get dirty and contaminated with bedding and there is always the risk that animals could drown. This is why it's recommended to use a water bottle or mouse drinker (Fig. 4) instead. The water container should be cleaned at least every second day and fresh water should be supplied if an open container is used. Closed containers should also be cleaned regularly.

1 Rat & Mouse Waterer Picture 2 Rat & Mouse Waterer Picture 3 Self-made Rat & Mouse Waterer 4
5 Cricket Waterer Cleaner 6    

 Figure 5  Rat & mouse drinkers. 1 & 2 Drinkers for wire cages; 3 & 4 Self made coffee bottle drinkers. 1 to 2 mm holes is drilled in the lids of these bottles and placed upside down with water. It is used on mesh cages & works especially well on mouse mesh cages. Make sure the animals, both large and small, can reach the underside of the bottle easily when used; 5 Bottle cleaner - useful to clean out algae from coffee bottle drinkers; 6 Bulk waterers also work well in larger containers when it can be kept clean. Make sure these waterers are not to deep for youngsters to drown.

Hamster or rodent food can be bought from almost any pet shop or large store selling pet goodies. Food mixtures containing sunflower seed, rabbit pellets, peanuts with or without shells, wheat, dog food and whole corn/maize can also be used. The proportion of sunflower seed, rabbit pellets and peanuts should be on the lower side as they are likely to provoke skin irritations on the long run. Commercial mouse cubes are produced by Epol® South Africa (+27 (0)12 386 0469) and are available in per 50kg bags.

Pet and non-breeding rodents only need to be fed according to maintenance. In this case almost anything can be fed ranging from low quality dog food to bread. Low quality dog food has a larger proportion of maize. Don't buy old cheap food! Two or three brands of low quality dog food can be mixed together to overcome mineral and other deficiencies that individual foods may have.

Suitable rodent supplements available from specialized vets or pet shops can be used for cheap or self-mixed foods. Always read the instructions or ask the seller to prevent incorrect supplementation. Fresh fruit and vegetables can also be used as extra supplementation. To prevent digestive upsets it's better to offer fresh foods in small amounts on a regular basis.

Pet rodents can be spoiled with treats such as dog biscuits or specific rodent snacks.

a b
 Figure 6  a & b Commercial Epol™ mouse cubes; c Wood shavings.

Cleaning, Bedding & Disinfecting
One layer of wood shavings is more than enough for rodent bedding. Finer wood shavings and sawdust may increase the incidence of irritation and respiratory problems. Wood shavings are available from most pet shops and some woodwork factories. Ripped or shredded pieces of newspaper, pieces of sponge and toilet paper can be added as optional environment enrichment. Shredded paper from office shredding machines is not effective if compared to wood shavings in absorbing water and urine and may lead to a cold wet floors and paper-cuts and should never be used as sole bedding for rodents. Rather use ripped newspaper. Make sure wood shavings are dust free and free from any dangerous insecticides.

Cages or containers should be cleaned once to three times a week depending on the number of animals per cage and the size and type of cage. Bedding should always be dry. The cage or container itself should be washed every time the bedding is replaced and disinfected at least once every two months.

Strong undiluted disinfectants may cause respiratory problems, skin problems and may even kill rodents and their young. Appropriate diluted chloride solutions like Milton™ or Jik™ are probably the best to use. Make sure to follow the instructions mentioned on the label. In most cases the solution can be diluted quite a lot, but also use your own discretion. Rinse excess solution off with clean tap water after wash, dry and let it sun dry for at least 20 minutes before re-use. Cages can be cleaned and disinfected in the presence of pups and kittns. Adults and babies can be carried over to a clean cage with bedding while the dirty cage is cleaned.

Babies can be separated from the mother for up to a day, but this and the cleaning of cages while there are babies can result in some degree of cannibalism by the mother, other females, other males or the father.  In spite of good success rates it is better to handle the young as little as possible and to clean cages only when necessary.

Hamsters on the other hand will almost always kill and eat their babies after handling of any sort by humans. Rather use clean gloves or toilet paper or something similar to handle babies when necessary. It is also interesting to mention that we have seen nursing mouse females raising dwarf hamsters.

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Breeding Rats & Mice:

A sexual active buck can be placed with up to six does (6:1 ratio). Two or more males per cage (especially small cages) can end up in brutal fights for domination which will ultimately end up in reduced fertility and matings. When a cage is too large a male can have difficulty in "catching" and mating with females. In this situation more males and females can be added although it might not be of any good.
    When using males in rotating systems, one should be at least three weeks with a female for ovulation and mating to take place.

Mice can get between 3 and 21 pups per pregnancy. Rats should be about the same but on average rats may have slightly larger litters, comprising ten or more kittns. Mice can conceive (give birth) about every 29 days. The gestation period or pregnancy (from fertilization to birth) is 19 to 21 days for mice and 21 to 23 days for rats. Rodents usually get pregnant and conceive while still nursing.

Rat kittns are usually weaned at the age of five to six weeks after birth. Commercially mice can be weaned at three weeks but the success will depend on the genetic strain. The suckling stage is very important for the development of any mammal. Milk is a very good source of calcium and proteins. The longer babies can be kept suckling the better. Hoppers are usually sold directly after they are weaned. Generally young can be weaned a few days after they start to eat solid food.

Puberty (sexual maturity) starts about six to twelve weeks after birth and is dependant on weight.

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Food Related Problems:

Deficiencies can rarely be seen when low quality, self-mixed or non-commercial mixtures are fed. The two groups that are theoretically most affected are the post-weaned growers and the pregnant and fostering females. Signs of deficiency include cannibalism, i.e. lower numbers of surviving pups and kittns and an overall reduced number of offspring born per pregnant female. Both males and females might also take longer to reach puberty or if a male is severely affected a whole group of females might fail to reproduce. All these signs will most often disappear very soon after a good quality food is introduced.

The most common deficiencies are probably protein and/or Calcium (Ca). Both these deficiencies can be prevented by feeding a balanced, pre-mixed or commercial type of food. Protein deficiencies can be supplemented to a degree by including peanuts or dog food in the ration. Nursing mothers or mothers late in pregnancy can develop Ca deficiencies, especially if dietary Ca sources are inadequate. This is due to the high commands for in utero foetus development and the initiation of milk production.

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Rat & Mouse Behaviour:

Generally rats tend to fight less among each other than mice, even after the introduction of new cage mates. Rats should as a breeding rule never fight among each other, not even among the same gender. This is usually not the case when they are not raised together. Aggressiveness is an unfavorable characteristic in pet rats and mice and should be a criteria for selection. Although mice are naturally more aggressive, the above rule should still be kept in mind. By not breeding with aggressive animals the incidence of the trait will gradually reduce in a breeding population.

The following situations can cause more than normal fighting among each other and aggressiveness towards the keeper:

  • more than two dominant sexual mature males in the same container

  • newly introduced males and/or females into an established group

  • females with babies

  • hungry, unfed animals

Fights among the same gender are common, especially among males and in smaller cages or containers. Males usually fight for dominance over their "territory". Note the difference between aggressive fighting and young animals playing among each other or males trying to mate with females. Females can get very aggressive towards new arrivals when they are nursing their young.

Neither rats nor mice should attack humans, even if they are under stress or have babies. Males and females should also not eat or kill their babies under normal circumstances (excluding handling, cage cleaning, transporting, underfeeding or anything else that may cause stress). These animals should NEVER be used as breeding stock.

Under normal circumstances animals might fight (sometimes brutally) when one or two new animals are introduced to a settled group. Never introduce single animals to settled groups, especially when one or two females have babies. The "attention" to new arrivals can be reduced by adding three or four individuals at a time or by introducing them directly after the cage has been cleaned. Rats and mice will explore their new clean environment and then establish the breeding and dominance pecking orders. Both males and females are territorial so by removing their pheromones and dominant smells the pecking order must first be re-established before unnecessary fights will happen.

Hungry, unfed animals might confuse a finger with a nice piece of meat. Parents might also kill and eat their babies for the same reason. Note the incidence of biting among each other, cannibalism and aggressiveness towards the owner might increase by feeding any type of meat and/or fresh blood containing products.

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Feeding Rats & Mice To Other Animals:

Rats and mice are excellent balanced food for other animals and can be fed to a variety of snakes, lizards and amphibians.

"One person's pet is another person's food... or feeder." - Melissa Kaplan.

The feeding of live animals has become quite a large topic over the last few years. It is seen as unfair, inhumane and cruel and is already banned in countries such as Europe, USA and South Africa. In South Africa the feeding of live animals is prevented in the Animal Protection Act 71 of 1962 (see the Acts section on RepVet.co.za for more info). For more info on this go to the Live Vs. Dead Prey and Preservation Of Live Prey sections on RepVet.co.za.

When breeding rats & mice primarily for food items, it is not to say they can be neglected & kept in horrible conditions!

All the stages of rats and mice are good sources of protein and minerals. Older rats and mice have more minerals like calcium (Ca) and phosphor (P) accumulated in their bones. The availability of these minerals reduce the likelihood of metabolic bone disease (MBD) and probably explains why rodent eating snakes almost never get this disease. Pinkies have less minerals compared with adults, but is a good source of fat and should never be fed as main diet to animals that are not solely rodent-eaters.

Adult mice and especially adult rats can be aggressive enough to kill their predators (see the Live Vs. Dead Prey section on RepVet.co.za for more info).

Start feeding small hatchling rodent-eating herptiles with day old pinkies and as the herp grows gradually increase the sizes to fuzzies, shrews or rat pinkies, adult mice, small rats, adult rats etc.
Adult Leopard geckos, some chameleons and frogs can start and mostly stay with small or new-born pinkies as an occasional treat. Medium to large Bearded dragons can go up to fuzzies and shrews and large snakes can go up to adult rats.

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Rats & Mouse Environment Enrichment:

Environment enrichment refers to a lot of things but one of them is providing an animal with something to keep busy.  Generally it can make a rodent feel more "at home" by simulating a bit of its natural environment. Today there are various rodent toys on the market like cages with tunnel systems, various nesting toys, exercise wheels etc. To keep a pet busy, home made items like normal clean toilet paper, ripped newspaper, toilet paper rolls, pieces of sponge and smallish pieces of wood can also be provided, which will increase nest building activity.

1 Rat & Mouse Environment Enrichment Picture 2 Mouse Exercise Wheel Picture    

 Figure 7  Rats & mouse environmental enrichment items. 1 Toilet paper roll insides; 2 Mouse exercise wheel.

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Potential Health Problems Of Feeder Rats & Mice:

Apart from cold temperatures mentioned above there is not much that can go wrong with a well fed colony of rats or mice.

Rodents are prone to some mite infestations. The Tropical rat mite (Ornithonyssus bacoti) infests especially rats. Engorged mites can be seen as little red organisms on various areas of the animals. They are blood sucking and may cause blood loss and anaemia. On direct contact they might infect and cause temporary irritation to humans.

Trauma leading to the loss of body parts and haematomas are also rarely seen.

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Feeder Rats & Mice Related Books:

We strongly recommend reading the following books on keeping and breeding feeder rats & mice:

Click on each book for more information

Keeping & Breeding Crickets As Feeder Insects by Renier Delport


Keeping & Breeding Crickets As Feeder Insects


"If you think I should add more information to this section or think that something is incorrect, contact me and let me know. I would love to hear your ideas or methods you might use that is different than ours."

Last updated 14 February 2007 by Renier Delport

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Related Topics:

Rats & Mice As Pets (RepVet.co.za)
Reptile & Amphibian Feeding Problems (RepVet.co.za)
Metabolic Bone Disease (MBD) In Reptiles & Amphibians (RepVet.co.za)
Live Vs. Dead Prey (RepVet.co.za)
Animal Protection Act 71 of 1962 (RepVet.co.za)
Preservation Of Live Prey (RepVet.co.za)

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Feeder Rats & Mouse References:

The Ultimate Encyclopedia of Small Pets & Petcare - David Alderton, 2001.

Miller, Stephen A. & Harley, John B. 1999 Zoology, Fourth Edition, McGraw-Hill.

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| Introduction | Classification | Biology | Stages | Sexing | Supermice | Handling | Keeping & Breeding | Breeding | Food Related Problems | Behaviour | Feeding To Other Animals - Ethics | Environment Enrichment | Potential Health Problems | Books | Related Topics | References |

[ Feeder Cockroaches ][ Feeder Crickets ][ Feeder Fly Ants ][ Feeder Hissing Cockroaches ]
[ Feeder Mealworms ][ Feeder Rats & Mice ]
[ Dusting & Gut Loading ][ Feeder Insects For Sale ]
[ eBooks ]
[ Feeder Insect Home ][ Email This Site ][ Contact Us ][ Links ]

Keeping & Breeding Crickets As Feeder Insects by Renier Delport

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