Stick insects are herbivores, which means they only eat plant material. They are especially fond of leaves, though some species will also eat stems as well. The key to successful feeding is to know what species you have and what its preferred food sources are.
Most stick insects kept as pets or in schools will readily eat eucalyptus leaves. You simply cut leaves off a eucalyptus tree (as a small bunch still on a twig) and put the stems in a small receptacle of water. The insects will eat them gradually over a couple of days. It is a good idea to keep an eye on the eucalyptus though, just to make sure it doesn’t dry out.
If you don’t have access to eucalyptus, no worries. Most species of stick insects kept as pets can eat other types of food as well. Common choices include the leaves of:
Also rest assured that stick insects have an innate ability to avoid food that would harm them. If you are introducing a new type of food and notice your insects will not eat it, assume it is not appropriate to that species. Try something else.
Putting Food in the Enclosure
If there are two words that best describe the most important aspects of feeding stick insects, they are freshness and water. Stick insects do best when their food sources are fresh. As such, it is recommended that you change out leaves every few days, even if the ones in the enclosures are not entirely consumed. Leaving food too long may result in your insects not eating at all.
As for water, stick insects derive their water from the plants they eat. This is one of the reasons experts recommend putting leaves in small dishes of water. As a side note, containers should be fairly shallow. A container that is too deep poses a risk inasmuch as a smaller stick insect could fall in and drown. So use a shallow container that’s just big enough to hold the leaves.
Gathering Your Food
Most stick insect owners gather their food from the wild. They will take a drive out to the country where they find an ample supply of leaves. If you are in an urban environment, you can buy appropriate food at pet stores, nurseries, and even grocery stores.
The below listed articles are all lengthy pieces on relevant topics related to the the feeding habits and food of stick insects.