Question: Today I saw a creature in a large cocoon made of sticks. Its head was black and orange, but the rest of it was inside the cocoon. Can you tell me what it was, whether it’s a native species and how it made its spectacular home?
Answer: Thank you for contacting the Discovery Centre at Melbourne Museum about the creature you saw in a cocoon of sticks. It is difficult for us to give you a definitive identification without seeing a photograph or the animal itself, but the creature you’ve described sounds very much like the native Saunders' Case Moth, Metura elongatus.
Case moths spin their cases out of silk and most species attach leaves, twigs, sand or soil to the outside for protection and camouflage. There are a number of different species and each species builds a distinctive-looking case. However, as individual case moths use whatever materials are available to them, there can be considerable variation in the appearance of cases within a species.
The Saunders' Case Moth is one of the largest species of case moths in Australia – their cases can be as large as 15cm long. Individuals of this species cover their cases with little pieces of twigs. They poke the front end of their bodies out the top of their case to feed, collect case decorations, and cling to surfaces as they move about.
As they grow, Saunders' Case Moths expand their cases from the top (head) end, adding additional twigs as they go. They do this by cutting off appropriately-sized twigs, attaching them temporarily to the top of the case and then disappearing inside to cut a slit where they plan to attach the new stick. This is no mean feat. Case moth cocoons are incredibly tough; cutting a slit for a new stick can take over an hour!
Case moths spend most of their lives in the caterpillar phase; this part of their life cycle can last 1-2 years. As caterpillars, they never leave their cases. However, they can be very mobile, dragging their large cocoons along as they move around. If they feel threatened they can seal off the end of the cocoon, cutting a new opening once the threat has passed. The females continue to live in their cases after they’ve pupated into adult moths, but the males leave their cases after pupation to fly off in search of females.
Hi Brett - It would be best to relocate the Moth by hanging it in a sheltered area (tree etc) not far from where it was found. If it isn’t pupating it can easily find its way back to the foliage where it originated. There is no easy way to know for sure if pupation is occurring short of destroying the case, so it would be best just to leave it where it is. If it doesn’t move for an extended period of time pupation may be occurring, in which case the only way to catch it if it is a male would be to place the case into a dry aerated container and check it each daily. We hope this helps!
If the case moth hasn't moved on yet you could try if you have a pair of tweezers to try and gently hold the very end of the case where it meets the tent and try to apply gentle pulling pressure and see if it will let go. Don't grab the case moth anywhere but at the very end of the case as you may well squash it. Once you have it off, just place it on a nearby tree. Good Luck.
Hi Frances. Perhaps follow the instructions for moving the case moth that we have previously posted for Caroline. Carefully move the case moth and place it in a nearby tree. Good Luck!
Hi Isabella, they are great insects to watch. The Museum has not reared this species before but apparently the pupation period can last from a couple of weeks to a couple of months depending on the season and weather. After this period if the insects are males the adult moths will emerge to fly off looking for females. If the individuals are females they will remain in their case, (they emerge from pupation as a wingless adult), and wait for males to find them. Good Luck with your case moth.
Hi Anita - A Case Moth caterpillar will remain in its case for several weeks if not months as it feeds and grows. Sometimes they will apparently close off the case for a few days and then move on to feed elsewhere. It’s only when the caterpillar is finished feeding that it permanently seals off the case to pupate within. If it turns into a male it will, after pupating, leave through the bottom of the case and go off in search of a female. The females are wingless and so emerge from the pupa and remain within the case for the rest of their lives.
Unfortunately, the caterpillars are heavily parasitised by tiny black wasps, which take a heavy toll. In order to follow the fate of this particular caterpillar you’d need to monitor its progress closely as most of the action occurs unseen within the case.
Hi Boggabilla Central School Year 1 class, I am glad that the information on our website was of interest to you and helped you to learn about what you had found. As you can see we have received a large number of comments and questions about the case moth. The Museum is not currently rearing this species but other readers of this website may be interested in anything you find out about the case moths you are finding and looking after. So please feel free to post any interesting or unusual actions or behaviours that you think other readers may find useful.
Hi Julz, I think you'll find that some others have asked similar questions, this was our response: apparently the pupation period can last from a couple of weeks to a couple of months depending on the season and weather.
Hi Sam, if the insects are still on the bush are you able to take a couple of good quality images and email them to email@example.com so we can attempt to see what species they are and provide some information.
Hi Karel, It sounds like a caddisfly and it could be in the family Limnephilidae, which has quite large larvae and is really only seen above about 1000m. If you have an image, send it in and we get the Entomology staff to take a look.
Dale - The creature is a Case Moth (probably Oiketicus elongatus). Case Moth caterpillars build a silken case which they often line with short twigs, and they live in this case and carry it around throughout the caterpillar stage, enlarging it as they grow. The caterpillar will poke its head out to feed, and when not feeding retreats back into the case and seals up the entrance.
If you want to keep it, you can feed it cut branches from a range of plants in the garden to see which one it likes best.
When it is finished feeding and ready to pupate, it seals up the case permanently and turns into a pupa. It will stay like this for several months and emerge as an adult in the spring. Males are small brown moths and fly away as soon as they emerge, but females are wingless and remain in the case throughout their adult lives.
Hi Bernadette, if you take it to show and tell make sure you handle it gently and try not to squeeze it as you may damage the insect inside. If you have to apply pressure try to always do this at the very ends of the case. After show and tell you could put it back where you found it, (or nearby), and let the pupation continue.
Hi Carrie, apparently the pupation period can last from a couple of weeks to a couple of months depending on the season and weather. After this period if the insects are males the adult moths will emerge to fly off looking for females. If the individuals are females they will remain in their case, (they emerge from pupation as a wingless adult), and wait for males to find them.
Hi Lisa, don't be too concerned about the case moth. These insects can be quite mobile and if it is not getting the nutrition it requires from the tree it is currently on it will move to a new food source. Enjoy watching her.
Hi Helen, the pupation period can be a few weeks to a few months, depending on the season and the weather. So if it has only been a couple of days since you saw the larva it is very unlikely that it could have pupated in that time.
We are not aware of there being any serious risk of infection resulting from handling case moths. However, there are some caterpillars in other moth families which possess hairs capable of causing irritation. Your son should avoid handling any furry or hairy looking caterpillars or any cocoons that look to have a spiky or hairy appearance, see the link below.
I hope your doctor was able to confirm for you the cause of the eye infection and that your son is well.
Hi Royce. If the case hasn't moved for a week it's likely that its previous owner has already flown away!
Hi Faerie, Saunders Case Moth larvae feed on tea trees, eucalypts, paperbarks, silver wattle and many other plants including garden ornamentals. The female Saunders Case Moth don't leave their cocoons after pupation, whereas the males emerge from the cocoon and fly to find females to mate with. So if you had 2 caterpillars they would not have been trying to mate. I haven't heard of them being territorial either, so I am not sure what was behind the behaviour that you observed.
Hi Martin and Karen,
We have never read anything or heard from anyone that these case moths actually smell. The Museum is not involved in control of insects so can't offer advice in this area. The case moths can be highly mobile, so while it sounds like you both have significant numbers at the present it is quite possible that they may move on. We haven't had reports of these caterpillars staying for long periods of time in the one place.
Hi Michael - our entomologist would love to see your photos. You can email them to the Discovery Centre at firstname.lastname@example.org. Thanks!
Hi Lucy, unfortunately we can't give a definitive answer on this one as the Live Exhibits Department have not had experience with keeping and rearing this particular species. One of the staff there has said that he is aware that some other brightly coloured caterpillars do lose colour before pupating. He has also seen some brightly coloured caterpillars lose colour before dying when kept in captivity too.
Hi Chris, I have asked the staff in Live Exhibits regarding your case moth caterpillar and they are not sure about the behaviour you have observed. We have not raised this species at the Museum and so have not had experience in watching it progress through pupation. Sorry we couldn't be of more assistance. Maybe someone else will add a comment if they have seen similar behaviour.
Hi Nadina, the female does not leave the case after pupation, only the male develops wings and can fly. This website, Saunders' Case Moth will show you images of the mature male moth.
Hi Chris, I don't believe you can determine the sex of Saunders Case Moth in the larval form. You need to wait until after pupation at which point the winged adult male moth emerges from the cocoon while the wingless adult female remains inside.
Hi April, these caterpillars can be quite mobile and you can relax in that the caterpillar should be quite capable of moving to a suitable food source when it feels the need to. It may be ready to pupate which means it will not be moving, so don't panic if this is the case.
Hi Lucy, unfortunately the Museum is not involved in control of insects so we are not well placed to provide advice on this subject. You could try an Internet search for 'control of case moths' or maybe your local nursery or garden centre may be able to assist you.
Case Moths feed intermittently, as do Spiny Stick Insects, so there is plenty of time throughout the day (and night) for both species to get their fill. Case Moths feed on a range of plants with other insects regularly disturbing them - including other Case Moths when they are present in high numbers - so you don't need to be particularly concerned about the wellbeing of either species.
Hi Michael,Unfortunately we cannot identify insects from a description alone. You can submit photographs through our Identifications service.
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