Care guides for feeder insects
In order for a gecko to remain healthy it must be fed an appropriate diet, where the nutritional content of the food available is maximised. It is therefore essential that good care is taken of any insects that are to be offered as feeders to ensure that they are as healthy as possible. This includes not only offering them good quality food, but also maintaining hygiene levels by cleaning their enclosures regularly so that any dead feeders and food debris is removed. A variety of feeder insects are commonly available either from pet shops or from online suppliers, including: silent crickets; black crickets; locusts; mealworms; dubia cockroaches and phoenix worms. All these species have different husbandry requirements, with a different range of temperatures and humidity levels being required to keep the feeders healthy.
Silent crickets or Jamaican field crickets (Gryllus assimilis)
Silent crickets are very susceptible to high levels of humidity, which will rapidly kill them; they should therefore be housed in a well ventilated enclosure such as a deep faunarium or a Kricket Keeper. As silent crickets are a tropical species, they should be kept at slightly higher than room temperature; ideally they should be housed at between about 25°C and 30°C (77°F and 86°F). In terms of decor, sheets of cardboard such as egg cartons or the inner tubes from rolls of kitchen towel will provide the crickets with somewhere to hide. As humidity must be kept to a minimum, it is highly advisable not to place a bowl of water in the enclosure; it is far preferable to place a few thin slices of 'wet' fruit or vegetables (e.g. apple, carrot or potato) in the enclosure to provide a source of moisture for the crickets instead (this will also prevent the crickets from drowning, which they inevitably do if a dish of water is offered).
Black crickets (Gryllus bimaculatus)
Black crickets are even more susceptible to humidity problems than silent crickets, so housing them in a well ventilated enclosure is a must, as even brief exposure to moderate levels of humidity will result in their death. Again, they should ideally be housed at temperatures slightly above room temperature, so between about 25°C and 30°C (77°F and 86°F), with egg cartons or similar provided to give them somewhere to hide.
Locusts or hoppers (Schistocerca gregaria)
Locusts (which are also known as hoppers when immature i.e. before their wings develop fully) are excellent feeder insects, though unfortunately they are considerably more expensive than crickets. They are slower moving than crickets, which seems to make them easier for geckos to catch; they are also less prone to escaping from vivaria than crickets. Again, they are best kept in a faunarium or Kricket Keeper in order to keep humidity levels as low as possibly. In terms of temperature, locusts should ideally be kept at 28°C and 30°C (82°F and 86°F). However, locusts tolerate low temperatures for limited periods well too; if feeder insects are ordered online during a period of cold weather, locusts frequently survive the period between despatch and delivery far better than crickets.
Mealworm (Tenebrio molitar)
Mealworm are the larval stage of a species of darkling beetle and are commonly available in two sizes: standard (which are suitable for larger geckos, such as adult leopard geckos) and mini mealworm (which can be offered to smaller species and hatchling leopard geckos). They are much more tolerant of low temperatures than other commonly available insects; indeed, in order to prevent them from entering the pupal stage, and therefore to increase their longevity, they can be forced into dormancy by being placed in a refrigerator, where they will survive for several weeks. Mealworm should be removed from the refrigerator at least 24 hours before being offered as food, so that they can be gut loaded properly. Once out of the refrigerator, they should be kept at normal room temperatures; I keep mine in a low faunarium.
Dubia cockroaches (Blaptica dubia)
Dubia roaches are possibly the most popular of all feeders among my geckos; all geckos large enough to be offered a dubia roach will happily take it. Dubias are unable to climb glass or fly, so are probably the easiest roach species to confine within a vivarium with little chance of them escaping. Even if they did, they are a tropical species and are therefore highly unlikely to be able to reproduce, as they require high temperatures in order to do so. Dubia roaches are best housed in either a large, flat faunarium or a Really Useful Box, which contains plenty of egg cartons and / or inner tubes from kitchen towels. The enclosure should be heated to a temperature of between 30°C -32°C (86°F - 90°F). Although dubia roaches are relatively expensive to buy initially, they will reproduce readily as long as optimum conditions are maintained; it is therefore extremely easy to become self-sufficient once a colony has been established.
Phoenix worms or Nutri-Grubs (Hermetia illucens)
Phoenix worms and nutri-grubs are brand names applied to the same insect - they are both the larval stage of the black soldier fly. Nutritionally, they make very good feeders, as they are relatively low in fat, but have a high calcium content. Their care is extremely simple; they require neither feeding (only a few drops of water are required periodically) nor do they have any specific heat requirements (though they should not be placed in the refrigerator). Unfortunately, I have had very limited success when it comes to using them as feeders; of all my geckos, only the D. tessellatus will take them very occasionally.
Gutloading
One of the most crucial elements in preparing feeders is to ensure that they are properly gutloaded before offering them to a gecko. The aim is not only to increase the overall nutritional value of the insects, but also to increase the amount of calcium they contain, as insects generally have a very poor Ca:P ratio. Before being offered to geckos, all feeders should therefore be gutloaded for a minimum of 24 hours.
In order to gutload feeders, I offer them: a variety of green vegetables (including cabbage, spring greens, pak choi etc); dandelion leaves (though care must be taken to make sure that these have not been sprayed with pesticides); potato; carrot; apple; pear; fish food pellets; and dog kibble.
I offer feeders small amounts of food regularly, rather than placing too much food in the enclosure at one time. I would therefore tend to place a good sprinkling of shredded green vegetables and fish pellets or dog kibble in the enclosure each day, together with a few thin slices of apple or potato. This method has several advantages: firstly, the insects (and therefore, the geckos) only get to eat food that is fresh and therefore has the maximum nutritional content possible; only offering a few slices of 'wet' fruit or vegetables at one time reduces the risk that the moisture they contain will make the enclosure too humid, which may potentially kill some feeder insects; finally, it will reduce the possibility that surplus food will start to rot and therefore cause the enclosure to smell.
Preparation of live food
As has been mentioned elsewhere on this site, in order to avoid the risk of Metabolic Bone Disease, it is necessary to dust feeder insects with both pure calcium powder and a calcium balancer containing vitamin D3 (such as Nutrobal). For adult insectivorous geckos, I would normally dust feeders with pure calcium twice per week and with Nutrobal once; for hatchlings and juveniles, I would use pure calcium five times per week and Nutrobal twice. Omnivorous geckos do not require their feeders to be dusted with Nutrobal as long as crested gecko diet is being offered as a staple, as this will contain the minerals and vitamins, including D3, that the gecko requires; however, I would dust all their feeders with pure calcium.
The easiest method I have found to dust feeders is to place their enclosure into a large, deep Really Useful Box or something similar; this reduces the risk of escapees. A section of egg carton or kitchen towel tube can then be removed and the insects clinging to it can be shaken into either a jam jar or small plastic bag. A small amount of supplement can then be sprinkled into the jar or bag, which should be shaken very gently to ensure that all feeders are coated in the fine powder. The feeders can then be released into the gecko's enclosure.
Preparation of crested gecko diet
Several brands of crested gecko diet (CGD) are now readily available, either from pet shops or for order online from specialist reptile supply stores. In my experience, the two varieties that are most readily accepted by geckos are the Repashy crested gecko diet, which is available for import from the USA from Pangea Reptiles and Clark's Diet, which is available in the UK from Clark's Gecko Diet. Both diets are sold in the form of a dry powder and, whichever diet is used, they need to be mixed with either water or puréed fruit. I have found that mixing the CGD with puréed water melon, honeydew melon and / or mango works well, as these fruits blend down to a consistency very similar to that of water; this makes mixing the CGD easier than if a thicker purée is used. I normally aim for an overall consistency similar to that of a thick milkshake; this normally requires a ratio of CGD: water or purée of approximately 1:2-3. To this I also add a very small amount of Manuka honey (literally a tiny blob on the very end of a teaspoon).
