Illinois Natural History Survey - University of Illinois

Silk Moths


Michael Jeffords and

Carolyn Nixon


hatching_Polyphemus.jpgGiant silk moths, such as Polyphemus or Cecropia, members of the family Saturniidae, can easily be reared in the home or classroom.   Before you start, you will need to build a cage to rear your larvae.  It should be at least 1ft x 1ft x 2ft tall, and should be covered with a fine mesh screen or cloth.    


1. Find a female moth, usually at lights during summer nights. Place her in a brown paper bag and close it up by folding over the top and creasing it. Check her in the morning. If she was ready to lay eggs, there were be several clusters of eggs attached to the paper. Release the female outside. (note: male moths have large, feathery antennae; female moths have narrower antennae with large, fat abdomens.)    


2. Eggs will hatch about two weeks after being laid by female moths. Watch them carefully so they do not starve!  They need to feed shortly after hatching and are very tiny at this stage.


Polyphemus_1st_instar.jpg3. Collect twigs with several leaves from a nearby tree of the correct species, make a bouquet with water in a vase and place the leaf bouquet inside the cage. Cover the top of the vase with cloth or paper to keep the caterpillars from falling into the water and drowning. You will not need a lot of leaves while the larvae are still small. This WILL change as they grow. Appropriate leaves for Polyphemus are Apple, Black Cherry, Dogwood, Elm, Maple, or Oak. Cecropia larvae will feed on Apple, Birch, Box Elder, Dogwood, Silver Maple, and Wild Cherry. Once you start with a particular tree species, keep that same species throughout the rearing process.


5th_instar_polyphemus.jpg4. Use a soft paintbrush to transfer the young larvae to the foliage in the cage. Be careful to not drop them or damage them in the move.


5. The larvae will settle down and eat, and eat, and eat . . .


6. When the leaves begin to wilt or dry or are all eaten, they must be changed. It’s best to create a new bouquet and just cut off the old leaves or stems that contain the larvae and clip them to the new foliage until they transfer over. This process will be repeated until they are full-grown and spin a cocoon.


mature_Polyphemus_larva.jpg7. Polyphemus moths will emerge in a few weeks. Cecropia moths have one generation a year.  Once your larvae pupate, put them in a mouse-proof wire cage, and keep them in an unheated porch or garage until spring.  They should emerge as adult moths the next May, so bring them indoors where you can watch them in late April. Place a male and a female in a paper bag, let them mate, and begin the entire process again.  


Alternately, if you find silk moth caterpillars (larvae), you can collect them and leaves from the tree they are feeding on, and proceed from #3.




    Adult female Polyphemus moth Adult male Polyphemus moth Polyphemus pupa


To identify adult and larval silkmoths, and to see a list of plants which the caterpillars will feed on, see Field Guide to Silkmoths of Illinois, by John K. Bouseman and James G. Sternburg, Illinois Natural History Survey Manual 9.


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