How to Breed and Incubate Stick Insect Eggs
Achrioptera fallax – an adult male
Stick Insects are possibly the easiest group of insects to rear and breed in captivity. As long as they have access to their preferred foodplant, they will grow, mate, and lay eggs without much fuss. For certain species of stick insects such as Extatosoma tiaratum, or leaf insects such as Phyllium giganteum, they do not even require any males to lay fertile eggs as they are capable of producing eggs through a mitotic process called parthenogenesis which gives rise to genetically identical offspring.
Breeding Environment for Stick Insects:
As mentioned in the introduction, stick insects are very easy to breed as they can be left alone and will mate and lay eggs without the need for any close monitoring – which is required for other insects such as praying mantis to ensure that the female does not kill the male.
Once stick insects reach adulthood, they will continue to feed and fatten up for approximately 1-2 months before they become fully mature and start to show signs of interest in mating. For parthenogenetic species, they will usually begin to lay eggs soon after the 1-2 month mark, and for non-parthenogenetic species, they will begin to lay eggs once successfully mated by a male and the spermatophore is absorbed. Depending on the species, the number of eggs can range from 1 to 10 per day. As with most insects, the female will store the sperm of the first male she mates with, meaning that she will continue to lay fertilised eggs from just a single mating.
Acrophylla wuelfingi – a fresh male and female adult pair
4 Types of Stick Insect Eggs:
Stick Insects can be sorted into four different groups when it comes to their egg laying method. Most of the commonly available species in the hobby are ‘egg droppers’ that will casually drop their eggs down onto the floor. The other types include ‘egg buriers’ that require a pot of substrate for them to dig and lay their eggs in, ‘piercers’ that pierce holes in various places such as leaves and leave their eggs there, and ‘egg gluers’ that stick their eggs onto various surfaces such as leaves and twigs using a sticky substance that dries and hardens upon laying.
Examples of stick insect species that lay their eggs in various ways:
Dropped – e.g. Achrioptera fallax, Carausius morosus, Extatosoma tiaratum.
Buried – e.g. Eurycantha calcarata, Haaniella spp., Heteropteryx dilatata.
Pierced – e.g. Asceles spp., Loxopsis spp., Paraloxopsis spp. .
Glued – e.g. Calvisia spp., Marmessoidea spp., Neoclides spp. .
Achrioptera fallax – eggs
Incubation Mateirals:
Any plastic container can be used to incubate eggs of stick insects, as long as it is wider than tall, and there are sufficient ventilation holes. Suitable examples include live-food tubs, or tupperwares that have had a large section of the lid replaced with mesh.
For eggs of most stick insect species, a thin layer of substrate should be placed on the bottom of the incubation container which will serve as both soft bedding for the eggs, and as something to absorb water and hold moisture. Examples of substrates that can be used include: kitchen paper, vermiculite and sand. It is preferable not to use soil as the bedding substrate as it has a tendency to contain organic material that rots easily, allowing the proliferation of bacteria and fungi that can damage the developing embryo inside the eggs.
For eggs of stick insect species that bury their eggs, a shallow bowl can be placed inside the incubation container filled with about 2cm of vermiculite in depth. The eggs can then be lightly buried with the operculum facing up (operculum = lid of the egg where the hatchling emerges from).
Achrioptera fallax – eggs in incubation on sand
Incubation Conditions:
Stick insect eggs should be incubated at temperatures between 20-26C, which tends to be room temperature for most homes, so extra heating is usually not required. Eggs do require some humidity which can be provided in the form of wetting the bedding substrate (kitchen paper / sand / vermiculite) which will then evaporate and provide a humid environment inside the incubation container.
When it comes to humidity, there is one thing for sure – less is always better than too much. The incubation container should be well ventilated as excessively high humidity levels severely increase the risk of mould and bacteria outbreaks which end up invading the egg through the operculum and resulting in the death of the embryo. Therefore, eggs should not be sprayed directly, and water should only be added in the form of drops onto the bedding substrate until it becomes moist, but not too much that it becomes wet. Once water is added to the bedding substrate, water should not be added again until the bedding almost dries out, much like when watering most houseplants. The frequency of adding water to the bedding usually tends to be once every week depending on how dry your climate is.
Incubation Length:
Stick insect eggs can vary greatly in terms of the length of incubation depending on the species. Some can hatch incredibly quickly after just 2 months of incubation such as certain Marmessoidea species, or up to 14 months of incubation for some species such as Heteropteryx dilatata.
Phasma gigas – an adult female