Caring For Luna Moth Caterpillars -- by Pat Schuler, the butterfly lady

Of all the North American silk moths (Saturnidae) my favorite is the pale green "luna moth" (Actias luna) . When all goes well with weather and everything else that could go wrong for the moths and their young, Lunas will emerge (eclose) from their silken cocoons in the Spring, mate, and lay eggs. The eggs will hatch into tiny caterpillars, which will feed eagerly, and grow rapidly, reaching full growth by mid-summer. At that point they spin their own cocoons to begin the amazing change we call "metamorphosis" , by which they will become new Luna moths. Within a few weeks these late summer moths will have left their cocoons, found mates and repeated the entire cycle of life all over again. This second generation will cocoon in the Fall of the year, to emerge in the following Spring. In our captive breeding program this second brood spends the winter as cocoons in the spare refrigerator we keep downstairs. Kept in plastic food safe boxes at a constant 38-40 degrees they rest until the weather outdoors is warm enough to signal the time to come out , mate, and begin the whole cycle of life again. I never tire of watching this miracle unfold , although it entails much work on my part. Cages have to be cleaned, the correct food gathered and fed, and caterpillars continually watched for any sign of disease.                                                                                                                                                                                                                                                                      
This year the cocoons were taken out of the " frig " and put into the large "emerging cage" about three weeks after Easter, on May first; and the moths began to eclose a few weeks later, on May 27th. That day, a lovely female emerged, and was put into the breeding cage after dark. The breeding cage is a cylindrical cage made of wire mesh with spaces large enough to permit the male to put his abdomen through for breeding, but not large enough to allow the female to escape. I set the cage on the table on my open back porch and checked on it every few hours over night to see if the female attracted any suitors. When checked at 12:24 A.M.there was no activity, but an hour later one male was mating with her and another flying around trying to get in on the action. The female attracts potential mates by emitting a pheromone, which males can detect from a mile or more away, and which is a powerful sexual attractant to males of her species. Once the two are attached, they remain so for up to 24 hours. After draping a towel loosely over cage and moths to protect them from hungry birds, I moved all to a quiet part of the porch and waited for them to separate. They did so the following evening, and the male flew off in search of another girlfriend. The female I put into a paper bag for a dark and quiet place for egg laying. After a day of laying eggs for me to raise, she was released to fly off in search of a suitable host plant on which to deposit her remaining eggs. These large moths may lay hundreds of eggs, most of which serve to provide food for birds and other wild creatures. I have heard estimates that only ten percent of moth eggs will go on to hatch and reach full adulthood. My own experience of releasing caterpillars on a small pecan sapling and observing the steady decline in numbers suggests the true survival may be much below that ten percent figure.
The eggs laid in the paper bag, plus what I found in the breeding cage ,were gently removed and placed in several plastic sandwich tubs to await hatching. Ten days later the first hatchlings were seen. I kept the first three days of hatchlings and put the rest of the eggs on to a suitable host plant ( pecan tree ) , not wanting the larvae I would be raising to differ too much in size. During the first week or so after hatching the larvae are so tiny they can be kept in the sandwich tubs , but the remaining eggs in each tub must be removed to other tubs until they hatch. At this size, the only food that should be provided is small pieces of the chosen leaf. Also, the lids of the tubs should be on tight , since the main danger at this point is dehydration. They will have plenty of air. No need to provide ventilation. The caterpillars will have eaten some of the shells of their eggs and have tiny stomachs, but should begin eating the leaves within twenty four hours. The first evidence that they are feeding may be little black dots on the bottom of the tub --caterpillar "frass". Yes, that's what we call insect "poop"!
It's very important, as the cats grow, to keep the tubs clean. The babies eat constantly and produce an awesome amount of frass. I generally find it necessary to clean containers and provide fresh food twice a day. As they grow larger, of course, larger quarters must be provided. Overcrowding produces stress, which lowers resistance to disease. An old aquarium with a well fitted lid can suffice, or a plastic storage tub with a cover will work. If I have a large number of large caterpillars, I use a cage I made myself with plywood and screening.
Sooner or later, of course, the babies reach full size and begin to spin cocoons. That's what my present caterpillars are doing now, and I'm breathing a sigh of relief. Now I can relax for a few weeks, or at least until the next generation begins to emerge and start the whole cycle over again. Considering the amount of work involved, I'm often asked why I am willing to do this each year. The answer is simply that it gives me such pleasure to play some small part in one of God's awesome wonders, the turning of a crawling creature, intent only on eating, into a lovely, winged being. Then, there is the symbolism of His turning a self-centered human into a new creation through faith in Christ.
"Therefore, if anyone is in Christ, he is a new creation; old things have passed away, behold, all things have become new." II Corinthians 5:17