MadSci Network: Zoology

Re: Raising a Wooly Bear Caterpillar

Date: Fri Nov 5 11:38:47 1999
Posted By: June M. Wingert , RM(NRM), Research Associate, Comparative Pathology Department, Baylor College of Medicine
Area of science: Zoology
ID: 941739462.Zo

Hi Emily,
The following care sheet should give you all the information 
you need to know in order to take care of your Wooly Caterpillar.
 There are over 140,000 species of
 Butterfly and Moth (Lepidoptera) in
 the World. They represent some of the
 largest and most beautiful insects to
 some of the smallest and most easily
 over-looked (unless you're an
 Entomologist). Caterpillars are the
 main feeding stage in the life cycle of
 butterflies and moths, and are one of
 the best "Creepy Crawly" Pets


 Caterpillars of many different moth and butterfly species can be
 obtained by post from many good entomological suppliers (a list
 of these can be found in the Links Section). However, many
 excellent caterpillars can be found by searching plants or
 bushes around you homes during spring and early summer.
 When you find a caterpillar remove the plant stem that it is
 feeding on and place this is a suitable carrying vessel (eg. Jam
 Jar or Sweet jar - with a lid!). WARNING: Do not try and pick up
 the caterpillar with your fingers as they are quite delicate and
 many possess hairs or secretions that are extremely irritating to
 your skin - collecting the stem they're on is much safer. Never
 take lots of caterpillars from a particular site, five is probably a
 maximum and the number taken depends on the size of
 enclosure you have prepared at home before collecting the
 caterpillars. It is also very important that you record the type of
 plant the caterpillar was found on and also take some stems to
 put in the enclosure at home. 

 If you find a caterpillar wandering along the ground then it is
 either searching for a food plant or looking for somewhere to
 pupate. If it is small then it is best not to collect it unless you
 know the exact species of caterpillar and the plant that it feeds
 on. NOTE: there are many, many species of small green
 caterpillar and unless you know exactly which one it is then it is
 likely to starve to death because you can't provide it with the
 correct foodplant. 


 This very much depends on the size of your caterpillars and how
 big they grow - you may need to re-house your pets as they get
 larger. Normally a tall sweet jar will be ideal, drill some small (ie
 smaller than the caterpillars) holes in the lid (Get an adult to help
 you) and place the stems of the food plant in a small jar full of
 water. It may be a good idea to block the top of the small jar with
 cotton wool to stop your pets climbing in and drowning. If your
 caterpillars are very small then you can use a block of oasis (a
 type of hard green sponge used for flower arranging) soaked in
 water and with the stems pushed into it. Once the foodplant is
 placed in the larger jar then you can gently introduce your
 caterpillars - again using the stem they are sitting on. It is also an
 idea to place a twig in the large jar so that should the caterpillars
 fall of the stems they can climb up the twig back to their

 Where you keep the cage is very much up to you and the type of
 caterpillar you are keeping. If you have a tropical species which
 you ordered from a supplier then it is best to keep them indoors
 and they may even require more specialised conditions (consult
 your supplier). If you found your caterpillar outside your house
 then you can keep your cage outside however you must be very
 careful that it will not blow over in the wind or fill with water when
 it rains. 

 You should spray the cage lightly with water once a day or so,
 however avoid large quantities of condensation forming on the
 inside of the container. Caterpillars can easily drown in
 condensation, remember that to caterpillars, a blob of water is
 very much like a lump of syrup the size of a small car is to us ie:
 very sticky and difficult to escape from. 


 The majority of caterpillars are herbivores (ie they eat vegetation)
 although many will become cannibals if not given enough
 foodplant. Aside from cannibalistic tendencies some caterpillars
 will kill and eat caterpillars of other species of moth and butterfly
 and it is best to keep them singularly (eg Anthocharis cardamines
 - Orange Tip Butterfly). 

 Caterpillars are extremely particular of what they will eat. Every
 caterpillar species has a particular type of plant (or family of
 plants) that it is associated with. Caterpillars will only eat very
 specific plants, which is why you MUST remember what plant
 you collected the caterpillar from - it is a good idea to identify the
 plant from a book or collect and press a stem for reference as
 your caterpillar grows. 

 As your caterpillars grow they will require more and more food
 so it is a good idea to make sure you have a good supply of the
 foodplant before contemplating keeping the caterpillar.
 Remember that the larger the caterpillars get the more they will
 eat. Caterpillars increase in size by moulting so don't be
 concerned if you see some with small bits of their old skin still

 As soon as most of the foodplant has been eaten or if it starts to
 wilt you must change it for fresh leaves etc. The replacement
 food should be exactly the same plant as before otherwise your
 caterpillar may not eat it, it is also a good idea to wash the
 foodplant thoroughly before giving it to you pets. I cannot stress
 enough how important it is that you feed your caterpillar the
 correct foodplant. If a caterpillar does not feed on it's specific
 foodplant then it may not feed at all and starve to death or will eat
 the plant but will never complete it's lifecycle and become a
 butterfly or moth. 


 As I'm sure you all know caterpillars must pupate as a chrysalis
 or pupae before becoming a butterfly or moth (Imago). During the
 pupation almost all of the caterpillar's body is broken down and
 the resulting 'nutrient soup' rebuilt into the body of the adult
 insect. When the caterpillars are full-grown they should be
 provided with suitable pupation sites. Butterfly caterpillars
 should be given stems and branches from which to suspend
 their pupae. Moth caterpillars producing subterranean larvae
 should be provided with a thick layer a damp peat, other larvae
 should be provided with foliage or bark depending on the
 species. If you are unsure of your caterpillar's requirements it is
 best to present them with a choice of pupation sites. Pupae that
 have formed during the spring or early summer may be left where
 they have been formed and should hatch within a few weeks.
 Pupae that have formed during the autumn will over winter and
 should be removed from the cage and stored to prevent them
 drying out or going mouldy. The pupae should be placed in
 layers of peat in small sealed containers; these should be kept in
 a cool but frost-free place until the following spring. In spring the
 pupae should be slightly embedded into a layer of peat or placed
 between the grooves of a sheet of corrugated cardboard. They
 should be misted with water occasionally to produce a humid
 atmosphere and this can be used to induce the emergence of


 When the adults are about to emerge you should place a number
 of twigs and stems in the emergence tank. The twigs are required
 by the butterflies and moths to climb up before expanding and
 drying their wings. If no suitable supports are available then your
 butterflies and moths will have deformed wings and be unable to
 fly. If you collected your caterpillars from the wild then you
 should release the emerged adults (or Imagos) in the same area
 as you collected the caterpillars. When releasing butterflies and
 especially moths (during the day) make sure that they are
 released in a fairly secluded area so as not to immediately fall
 prey to birds. 

 If you obtained you caterpillars from an entomological supplier
 and they are not a species native to your country or area you
 could try and breed them to produce another generation of
 insects. Information on breeding butterflies and moths will be
 available from the supplier of the caterpillars and from a number
 of AES Publications. 

 I wish you luck rearing your caterpillars but remember that if
 you've collected them from the wild then return the adults to the
 wild so there will be more caterpillars next year. 

 Copyright K.Pitts 1997 

 This Caresheet may be printed and freely distributed however it must be 
distributed in its entirety and
 remains Copyright to the authors and the AES Bug Club. This Caresheet may 
not be distributed for
 money or as part of a publication (electronic or otherwise) for which 
people must pay unless express
 permission is gained from the Author and/or AES Bug Club - see Contact 
Section. The Caresheet reflects
 the particular techniques used by the author to rear the relevant 
invertebrate however other techiniques
 may also be suitable. 


Thanks for taking the time to send in a question to the Mad Scientists 

June Wingert
Baylor College of Medicine
Houston, Texas

Current Queue | Current Queue for Zoology | Zoology archives

Try the links in the MadSci Library for more information on Zoology.

MadSci Home | Information | Search | Random Knowledge Generator | MadSci Archives | Mad Library | MAD Labs | MAD FAQs | Ask a ? | Join Us! | Help Support MadSci

MadSci Network,
© 1995-1999. All rights reserved.