If you are not familiar with keeping insects as pets the first thing you will notice as you gather information is that they are way more popular than you thought. Species kept as pets range from the alien looking preying mantis, star of more than one horror film to foot long centipedes big enough to eat pinky mice to specimens that are found in the back yard.
The most common types kept as pets are the Myriapods that contain the centipedes and millipedes, the mantises, roaches and stick and leaf insects. Centipedes and mantises are carnivorous and eat other insects, Roaches except for the group known as wood roaches are eat anything omnivores and the millipedes and stick and leaf insects are herbivores.
In general they don't need much room doing just fine in plastic deli containers but some of the bigger species may need a 10 or even 20-gallon aquarium. One thing they all need is a tight fitting lid to prevent escape. Being arthropods most need a warm humid environment and being insects many are nocturnal. Speaking about them in general is useful in getting a feel for this group of pets but given the large variety of species and their wide distribution this can also lead to trouble so learning about the individual species being kept is critical to your success. Lets look a little closer at some of the popular pet varieties.
The Myriapods include the centipedes and millipedes which at first glance seem pretty similar but are actually quite different. Both have long segmented bodies that in the centipedes tend to be flattened while the millipedes are rounder and more tube shaped. The centipedes have one pair of legs per body segment in contrast to the two pairs per segment of the millipede. Centipedes are venomous predators that can be dangerous to man but the millipedes are peaceful plant eating herbivores. This last part is very important to keepers both in feeding the right food and taking the proper precautions in securely housing and safely handling the venomous varieties.
The enclosure should have 2-3 inches of substrate for the centipedes and 4 inches or more for the millipedes that are avid burrowers. Species from drier climates should have a 50-50 mix of sand and coconut fiber or peat moss and those that come from jungle and forest habitats should have a 25% sand 75% organic mix. The enclosure should be misted to maintain humidity but should only be misted on one end to provide a moisture gradient that allows your pet to find a spot it is comfortable with. The enclosure for tropical species should have a heating pad placed under one end of the enclosure to provide a temperature gradient again allowing your pet to find its own comfort zone. Some leaves and bark should be provided for hiding spaces to make them feel more comfortable.
Feeding millipedes is easy they will eat just about any plant material which should be dusted with a calcium supplement for proper shell development. Centipedes being predators are usually fed crickets and roaches about once a week. Larger specimens can be fed small lizards or pinky mice but these are not necessary and pose a risk to the centipede when they struggle.
There are around 2000 species of mantis worldwide. Mantids usually range between 4 and 6 inches long depending on the sex and the species with females being larger and heavier bodied. All Mantids are predatory usually preferring flying insects, however they are also cannibalistic so mantis communities are not a good idea. In the northern hemisphere the species that normally comes to mind is the European Mantis (Mantis religiosa) which is native to Europe but has become widespread in North America after its introduction but there are many more exotic looking species like the orchid mantis (Hymenopus coronatus) and the Chinese mantis (Peruphasma schultei).
The Mantis habitat should house a single mantis should be about 3 times as high and about 2 times as wide as the mantis is long. Roaches, grasshoppers, crickets and a mix of other insects should be fed every 2-3 days.
Mention the name roach and most people picture scurrying hoards when the lights are turned on. These are the small german cockroaches made famous as the scourge of ghetto apartments in more movies and TV shows than you can count. These are indeed pest but in reality less than three dozen of the thousands of roach species are pest to man. The rest prefer to live in nature eaking out a living in the undergrowth and leaf litter or underground in caves and burrows. For instance the most popular pet species the Madagascar hissing Cockroach (Gromphadorhina portentosa) which can grow to 2-3 inches normally inhabits the forest floor feasting on decaying vegetation playing a key role in returning nutrients to the soil. Now that's a big roach but not the biggest, not even close, that title is held by the rhinoceros cockroach (Macropanesthia rhinoceros) from Australia that can fill the palm of your hand and weigh more than an ounce.
Most roaches are not picky eaters and most captive diets consist of cereals, fruits and vegetables but dog food is another common choice. Roaches are escape artists so their habitat needs to be tightly sealed. Species that live in leaf litter do well on a bed of wood shavings while those that burrow do best on peat or coconut fiber. Most pet species are tropical and need temps in the upper 70's so a heater is usually necessary for these. A roach habitat doesn't need to be very big deli containers and small plastic creature habitats work well for most. If you are keeping a bigger species like the hisser a half dozen or so make a great display in a 10-gallon tank.
The unique camouflage of the stick and leaf insects called phasmids make them a favorite of many insect keepers. These guys have often evolved to be almost invisible on a particular plant that they feed on. The ornate leaf insects tend to be pickier about what they eat and some species will only eat a single kind of leave.
Most species kept as pets come from tropical environments and there are laws regulating keeping exotic species in many areas. Because of their often very specialized ecological niche it is very important to research the specific species you plan to keep. Many will starve to death on a bed of the wrong kind of leaves.
A lot of the pet varieties also need more airy conditions than many of the other arthropods. These can be kept in a net cage available for just that purpose.
There are many more species of insects that can be kept as pets. Some of the more exotic varieties include the impressively horned rhinoceros beetle or the sinisterly named assassin bugs. However realize that just like any other pet they probably have pretty specific needs that must be met in order for them to thrive.
The best choice for a first insect pet might not be one that comes from halfway around the world at all. There are probably at least a few interesting varieties that can be found near you. Remember though that some insects can be poisonous so make sure that you never touch an insect that you are unfamiliar with.