Actias luna

While I generally write about butterfly life cycles, I am interested in Lepidoptera in general, and on occasion, I do raise interesting moths. Today, I will be writing a brief note about Actias luna, a beautiful North American giant silkmoth (family Saturniidae) commonly known as the luna moth. The family Saturniidae includes some of the world's largest and most beautiful moths, including the largest known as the Atlas moth (Attacus atlas). Some common features shared by this group of moths is that they pupate in cocoons and have no functional mouth parts as adults. Their only purpose as an adult moth is to find a mate and produce the next generation. The adult moths typically live only 7-10 days and survive on fat stores accumulated during the larval stage.

Actias luna is a common species in Canada and the USA, but is rarely encountered because of their short adult lifespan and the fact that most moths are nocturnal. This moth is found in the eastern half of the USA, and in Canada, ranges from Nova Scotia to the most eastern parts of Alberta. Although widely distributed, it is never extremely common in any particular area to be considered a pest. Most silkmoths have many natural predators and parasites which keep their populations in check. Only about 1% of all the eggs produced by a female make it to adulthood to further the next generation. In the north, this moth only has a single generation per year. Around NY and NJ, the climate is sufficient that one can find 2 generations per year. South of the Ohio valley, there are at least 3 generations. In Louisiana and Florida, adults can be found every month of the year. Depending on location and brood, there can be some variation in color, but generally, the luna moth is a beautiful pale green with a purple to maroon border on the leading edge of the forewings. Both the forewings and hind wings have conspicuous eye spots, and the hind wings have elongated tails which is unique among North American Saturniidae. The sexes show no constant wing differences but are easily distinguished by the large feathery antennae of the male and relatively slimmer antennae possessed by the females. When female luna moths emerge from their cocoons, they typically don't fly right away in order to conserve energy. Instead, they get the males to come to them by releasing a pheromone (chemical scent) into the air. The large male antennae are exceedingly sensitive to this scent and males can be attracted to a female luna moth from several miles away. Female luna moths generally have larger abdomens than the males, but using this characteristic alone to differentiate the sexes is not reliable since the female abdomen will decrease in volume as ova are laid. There are also ways to differentiate the sexes during the pupal stage. The larger size of the future male antennae are apparently by examining the pupal casing. However, the term "larger" is relative and unless one has a clearly female pupa for comparison, just how large is large enough is ambiguous. A better way to discern the sexes is the presence of two longitudinal grooves on the ventral surface of the fourth and fifth abdominal segments of female pupae which are lacking in males.

The easiest way to obtain Actias luna for rearing is probably during the adult stage. The moths are attracted to UV light and if one is lucky enough to capture a female, it is highly probable that she has already mated (or else she wouldn't be flying around probably) and will produce fertile ova. I did not look for this species on purpose this year, but a friend found one clinging to their kitchen screen one morning and was kind enough to alert me. I recognized that it was a female and placed her in a cardboard box to obtain eggs. In the wild, of course these moths will fly around and deposit ova on appropriate host plants, but in captivity, they will deposit their eggs on just about anything (they have nothing to lose). In fact, if a female is kept from mating, it will still deposit eggs after a few days even though all those ova would be infertile. Below is a female luna moth and some of her ova.

She didn't lay too many eggs for me, and I suspect that she was already several days old when found. Most of her eggs were probably already deposited in the wild. I was surprised because her wings were still in relatively good shape. Trying to obtain this species any other way is probably very difficult. Finding eggs and larvae would be like looking for needles in a haystack. Their cocoons are also very difficult to find because they are well camouflaged and hidden in the leaf litter rather than being affixed to a tree branch.

The female luna moth I had laid a couple of dozen ova for me. I knew that there was a good chance she had already mated, but one can never be 100% sure, and I waited anxiously to see if these ova would hatch. Luckily, about 10 days later, I had a bunch of tiny green and black larvae. Luna moth larvae are solitary feeders throughout their lives.

Actias luna larvae have been documented to use a variety of host plants, though there are regional preferences. For example, many sources will state that northern populations prefer white birth (Betula papyrifera). Some common host plants for this species includes birches, walnuts, hickories, butternuts, pecans, sumacs, sweetgum and persimmon. I raised my larvae on staghorn sumac (Rhus typhina) primarily because of ease of access.

The above pictures are of second and third instar larvae. Starting around the fourth instar, I set them on host plants outside, protected by mosquito netting, to finish the rest of their larval development. This is done for a few reasons. Many Saturniidae larvae do not do well when raised in large numbers in captivity. Crowding and poor air circulation put them at risk for infectious diseases and I did not want to lose what few larvae I had. As they grow, their food requirements also increase, and it becomes difficult to supply them with enough fresh leaves every day. It's easier to just put them on a living plant. Lastly, I also wanted to expose the larvae to natural temperatures and photoperiod so that they hibernate through the winter instead of emerging as adult moths in the fall. During the fourth instar, if larvae experience less than about 12 hours of sunlight, they will likely hibernate. More than 16 hours of sunlight per day, and they will develop directly into adult moths and skip the hibernation process. In between, well, you get a mixture.

Above are fourth and fifth instar larvae. Finally, when the fifth instar larvae are about to spin their cocoons, they change from bright green to a light maroon color, shown below. Fully grown larvae reach about 70 mm in length.

It should be noted that in general, it's the larvae which are going to hibernate that show this color change (rare exceptions). If the larva is going to develop directly into an adult moth, it will remain green prior to spinning its cocoon. The larva will take about half a day to construct its cocoon. The cocoon has a single compact layer and is rather flimsy compared to cocoons built by some of our other native Saturniidae.

After the cocoon is constructed, the larva inside will prepare to shed its skin one final time in 2-5 days (depending on temperature) to produce the pupa which will endure the cold winter temperatures. The pupae which go into hibernation need this cold period to break their dormancy and induce normal development. Cocoons may be stored in many ways during this period. Some people store the cocoons outside, protected by a container or mesh so that birds and rodents don't eat them in the winter. Other people leave them in an unheated garage. I keep my cocoons in the fridge, occasionally misting them to maintain humidity (some people don't mist and the cocoons do just as well). When spring arrives, the cocoons will be moved outside so that they experience outside environmental conditions and develop at the same rate as wild luna moths. This way, when the adult moths emerge, there will likely be other adult moths in the wild so that they can find each other, mate, and produce the next generation.

Adult moths typically emerge in the morning but afternoon emergences are known. Mating normally occurs in the first hours after midnight and the pair may stay together until the following evening. Egg laying begins the following night and continues for several nights. The ova are deposited singly or in small groups on both surfaces of a host plant leaf. Female luna moths can lay around 250 eggs but some large females can produce as many as ~400!

Lots of pawpaw

In October 2013, I posted some information about the Zebra Swallowtail and how it feeds on Asimina triloba (pawpaw) and a few other related plants. I was able to get a hold of some pawpaw seeds and so it's time to update what happened!

So, in that previous post, I talked about how these seeds must be cold stratified in order to break their dormancy so they can germinate. This can be done in the fridge over 3-4 months, but the seeds must not be exposed to freezing temperatures or they'll die. They also shouldn't be allowed to dry out. Those were the instructions I read on various websites, and so that's what I did. I was pretty busy and didn't have time in the spring of 2014 to plant the seeds. I didn't get around to doing that until the fall of 2014. I wasn't sure what would happen because the seeds would have been cold stratified for almost a year, and that doesn't happen in nature and I wasn't sure if the seeds would survive for that long. Fortunately, they did and were more resilient than I anticipated. I got about a 90% germination rate.

I had about 45 seedlings in total, and they only took a few weeks to germinate, much less time than I thought it would take. Most grew several leaves before they became dormant and all growth stopped. I wasn't sure exactly what triggered this since they were indoors all this time with more or less constant temperatures. Perhaps it was photoperiod?

Anyway, they stayed like that until the spring and that's when I decided to plant them in the backyard. I expected that the spring would break their dormancy and they would just pick up where they left off and keep growing. However, the plants lost the few leaves they did have and did absolutely nothing for the next several months! I was pretty bummed out - I thought they all died, and worse, I had no idea why. There didn't seem to be much more I could do except get new seeds and try again in the future.

By shear luck, I didn't bother getting rid of what I thought were dead seedlings, and to my great surprise, one day I noticed that some had put out new growths! They weren't dead, but just dormant.

So now I've got a bunch of happy pawpaw seedlings growing both in my yard and in the house. I'm not sure if the ones indoors will become dormant again this year, but for now they seem to be doing well and growing really fast. These above two pictures were taken 15 days apart. I'm also hopeful that the seedlings I have outside will survive the winter and keep growing next spring. They're not very big and because they were dormant most of this summer, they didn't really have a lot of time to grow and get established. Only time will tell!

More degreasing!

Okay, so the other day I noticed that another one of my specimens was stained with grease, and this time I remembered to take some pictures!

The above is a Vanessa virginiensis (American Lady butterfly) I spread recently. Unlike the sphinx moth specimen I degreased a while back, this specimen got stained with grease right away (within 2 weeks). You can see that the lower outer half of the left hind wing is stained. It has a brownish color and is more dull compared to the right side. The upper part is shiny where the light is reflecting off the grease. So, like last time, I poured out a small dish of acetone and put the specimen in and let it soak.

This picture was taken about 2 hours later. The improvement is easily noticed by comparing the medial lower aspect of the left hind wing with the right. The discoloration is gone. The upper outer part of the left hind wing is misshapen but that's just how the butterfly had formed (a birth defect if you will). One of the veins seemed to have a small break or kink and the surrounding wing surface was wrinkled. Some of the surrounding color is also a bit asymmetric.

This species does not exhibit a lot of sexual dimorphism - that is to say, the males and females don't look a whole lot different and it's very hard to tell them apart. Some websites will say that there is no easy way. However, this is not true! This specimen is a female and you can tell because the spots just below the mid leading edge of the upper forewings is orange in females and white in males.

The last year has been quite busy for me in terms of moving and starting a new job. I did still manage to raise a few new species, but just haven't had time to update this blog. I hope to post some new stories soon.

Specimen degreasing

So, the other day, I was checking on my specimens (a good thing to do as part of regular maintenance of a collection) and I saw that a sphinx moth I had collected a couple of years ago had become stained with grease. I'm not sure exactly when this would have happened. I have had this specimen for a couple of years and it was fine the last time I checked it (a few months ago). Anyway, as some of you out there may or may not know, dead butterflies and moths can occasionally become stained with grease. The abdomens of many species contain fat reserves, and when the insect dies, the fat can decompose and liquefy, and then it seeps out of the abdomen and can track along the wings and stain them. This leaves the wings discolored and can also give them a shiny greasy appearance. No one knows what exactly triggers this process, and it certainly doesn't happen for every specimen (probably a minority overall). It can happened soon after the insect dies, or sometimes as in my case, years later. Some species are more prone to this phenomenon than others though. Many of you may have noticed that quite a few of the Morpho specimens sold these days have their abdomens missing! When I was younger, I wondered why this was the case. I later found out that the abdomens are removed on purpose to prevent this staining phenomenon.

So, when this happens, can anything be done? Is the specimen permanently ruined? Well, as it happens, the specimen may be salvaged most of the time by degreasing in an organic solvent. If one does a search for this on the internet, you'll see that many solvents have been tried and are recommended, and there are advantages and disadvantages to many. I'm not sure there is a single best chemical agent for the job. Some commonly recommended chemicals are acetone, diethyl ether, toluene, xylene, and even gasoline. Many of these chemicals are either toxic when inhaled and/or very flammable. Some may be difficult to obtain for the average person.

I think acetone is the mostly commonly used because it's relatively safe and easily obtained. It's used for a variety of commercial purposes and can be easily located in most home hardware stores. The fumes are not very toxic (though limiting exposure is always a good idea), but they are very flammable, and so care must always be taken when working with acetone. Diethyl ether is probably a better agent for degreasing specimens, but the fumes are also very flammable and if stored for a long period of time, the ether can spontaneously form explosive peroxides. For the average person, I don't think xylene or toluene are easily obtained, although I have read that xylene is better than acetone or diethyl ether for degreasing.

For my purposes, I obtained a can of acetone from a local hardware store. I have never done this before and was a bit concerned about how well it would work and whether it might damage my specimen in the process. However, my sphinx moth specimen was badly stained anyway, and I figured, how much worse could it get? I read up on this procedure as much as I could and decided to just give it a go and see what results. It is generally recommended that this be done in a well ventilated area, and some people do this in their yard or garage. I decided to do this in my kitchen of all places and my ventilation was in the form of the kitchen fan on maximum, and it actually worked quite well. Acetone should be contained in glass or metal, as it can dissolve some plastics. You should also make sure that anything it can potentially damage near by is covered up (like the kitchen counter). Now, I wasn't sure what to expect at this point, and so I didn't take any before and after photographs, or document my set up, so I'll just try to be as descriptive as I can.

I poured the acetone into a glass bowl, and set both the can of acetone and the bowl on a flat metal baking tray on the kitchen stove. The fan had already been turned on at this point. You can certainly smell the acetone fumes (sort of a fruity smell) when you're directly over the open bowl, but as soon as I stepped away, the fumes were no problem. Make sure the stove is off of course! Next, I just took the specimen and completely immersed it in the acetone bath. I took off the specimen label first because the acetone can dissolve the ink sometimes. Some sources out there will say that the acetone can damage the insect pin, but I think this only happens if you're leaving your specimen in acetone for a long time, like a day or so. I had no problems with this but I only left my specimen in the acetone for about an hour. After the specimen was immersed, I covered the top of the bowl with a lid and just left it sitting (acetone evaporates very quickly). It should also be noted that acetone is less dense than water, and so if you don't suspend the specimen, it will just sink to the bottom of the container. For larger specimens with quite a bit of weight, it may therefore be a good idea to attach a piece of cork or similar object to the bottom of the lid, and then pin the specimen there so that it's suspended in the acetone once the lid is put on the container. That way, parts of the specimen will not touch the container and one decreases the risk of damage from the weight of the specimen resting on a wing edge for example.

When placing the specimen in the acetone, I was wondering if there would be a lot of surface tension. If you try to push a specimen into a bowl of water, you'll see it's actually not that easy, and the water doesn't easily wet the wings (a good thing when the insect is alive in nature). I had read some warnings that surface tension might break delicate parts of insects if this isn't done carefully (like tails on swallowtails or antennae). However, the acetone wetted the whole specimen easily. I intermittently swirled the bowl of acetone gently to help circulate the acetone around, but you have to be gentle so the specimen doesn't bump around the bowl and get damaged.

It's difficult to say how long one should leave a specimen in the acetone bath. Some say 10 minutes will do, while others treat the specimens for days using multiple acetone washes. This probably comes with experience, and I'm sure it also depends on how much grease there is in the specimen to begin with. For small specimens where there isn't much grease, an hour will probably do. Big saturniid moths may take days I suppose. The sphinx moth I had wasn't exactly small, but I found about an hour was actually enough, and there was no visible grease left nor damage to the insect pin. I think those who degrease for days are trying to dissolve all the grease from the insect body so that not only is the specimen clean, but there's no chance the specimen will be stained again in the future. While that would be great, I decided to just do the minimum and not risk any damage to my specimen given that this was my first attempt. Besides, this degreasing process can be repeated as often as necessary.

So after about an hour, I lifted the lid and gently took out the specimen. The wings and body had a wet look and it was hard at this point to tell whether the treatment worked. I held it close to the kitchen fan and also gently blew on the moth specimen. This helps the acetone evaporate faster, but the other reason I did this is because I read that sometimes hairs on the body and wings of insects can remain matted even after the acetone evaporates, and that having a light breeze during the drying process can help prevent this sequela. It worked perfectly and within a couple of minutes, the specimen was dry. I saw no trace of grease left on the body or wings - the specimen looked brand new! Some sources warn that the specimen may become loose on the pin or that the wings may move and require re-setting after degreasing, but again, I didn't find that an issue after such a short duration.

During the course of my research, I also read that because the acetone evaporates quickly and can also further dehydrate specimens which aren't fully dehydrated, it can sometimes cause the wings to wrinkle, especially wing tips. This didn't happen with my sphinx moth which was already a couple of years old and probably thoroughly dried. However, I subsequently tried the process with a fresh unpinned specimen and I did observe this phenomenon. I used a Papilio polyxenes asterius and the tails on the hind wings became curved and brittle, and when I subsequently tried to flatten this out, the tails broke. So, I think the lesson here is, if you're degreasing an old specimen it probably doesn't matter too much. If you have a newer specimen, you can either wait it out a bit or take your chances.

Some sources out there recommend degreasing as a preventative measure rather than addressing the problem after occurs. For this, to avoid badly dehydrating the specimen as mentioned above, what one would do is remove the abdomen, degrease it really well over days, and then glue this back on to the rest of the specimen after it has been spread. That way, there's no chance anything will be stained in the future. I suppose one can do this for every specimen, but I imagine it can be time consuming. One last thing I should mention is that I also read that for species containing green colors, if that is discolored by grease, the degreasing process cannot retrieve that color. I'm not sure why this is the case, and I don't have personal experience of this to comment further. I certainly have seen examples of blue morphos that have been degreased wherein the blue iridescence was brought back.

After the degreasing is complete, one is left with a bowl of acetone to dispose. I didn't just pour it down the drain because I wasn't sure if it would dissolve some of the plastic piping or not. A better idea is probably to just let it evaporate on its own. Some people suggest just leaving it in the back yard to evaporate - a good idea but you first need to make sure it's in a location not accessible to children, pets, wildlife...etc. A protected environment like the garage is probably also not a bad place to leave the acetone. You just have to open the door and air out the garage later on before use. I decided to leave my bowl of acetone in the garage. After a couple of days, the vast majority of the acetone had evaporated (probably the volume of a can of pop). What was left behind was a bit of acetone mixed with the dissolved body fats from my specimen. At this point, I could barely smell any acetone, and I just washed the bowl and poured the contents down the drain with lots of water, with no apparent ill effect. So, that was my first experience degreasing a specimen, and I feel quite pleased with how things turned out!

Papilio glaucus glaucus

Papilio glaucus is commonly known as the Eastern Tiger Swallowtail, and is one of the most common and easily recognized butterflies in North America due to its contrasting yellow background and black stripes resembling those of a tiger. This species is found in the eastern half of the USA and extends into southern Canada reaching as far as Ottawa, Ontario and parts of southern Quebec. There are two subspecies: maynardi in central and south Florida and glaucus in the rest of the range. These two entities fully intergrade in Florida, but there are demonstrable morphologic and physiologic differences between the populations (see PhD dissertation by Matthew Lehnert, University of Florida, 2010). In Canada, there is a closely related sister species, Papilio canadensis (Canadian Tiger Swallowtail), which was once considered a subspecies of Papilio glaucus. However, nearly 25 years ago, they were separated as being different species based on a number of characteristics including morphology, food plant use, and biochemical/molecular analysis. I'm currently raising some Canadian Tiger Swallowtail larvae, and will write a more detailed entry on this species in the future. There is a thin zone of hybridization between glaucus and canadensis where their ranges meet, and anecdotal evidence suggests that this zone has been moving northward in recent years, likely due to climate change. In Ottawa, Ontario for example, Papilio glaucus was once very rare, but is now regularly seen.

Papilio glaucus is one of the most polyphagous swallowtail species known, meaning that its larvae will feed on numerous types of host plants, as opposed to being restricted to just one or a few species. There are so many that I am not going to list them all, but some common ones include cherry, tuliptree, and ash. I typically find ova and larvae on tuliptree (Liriodendron tulipifera), but I'm biased because I really don't focus on the other potential host plants. The green eggs are spherical, about 1 mm across, and laid on the tops of leaves. One time, I also found an egg on hoptree (Ptelea trifoliata) incidentally, which is a known host plant for this species.

After hatching, the caterpillar is black with a white saddle across its mid section, making it resemble bird poop. There may also be a very small patch of white near the back end of the caterpillar.

The larva goes through 5 moults, and the stage between each moult is known as an instar. So after hatching from the egg, you have a 1st instar larva. After the first moult, it has reached the 2nd instar, pictured below. As you can see, it's not dramatically different in terms of overall color, but just larger that's all.

Starting from the 3rd instar, one begins to notice some color changes. The larva becomes just a bit more green and mottled, and there are also now noticeable blue spots placed transversely along some segments. The second picture below also shows the caterpillar's osmeterium. This is an eversible organ that the caterpillar displays when disturbed. It emits a rather pungent odor, and is meant to ward off potential predators. In fact, it is a defining feature of all larvae of the swallowtail butterfly family.

The 4th instar larva is now mostly green but you can still see a remnant of the white saddle it had as a 1st instar larva. You can also see that the larva now has fake eye spots behind its actual head, which is tucked close to the leaf. The green color helps the larva blend in with the foliage, but should it be discovered, it's believed that the fake eye spots may provide some additional protection by startling the predator. Perhaps the caterpillar is trying to mimic a small snake or lizard. In the second picture, you can see the larva just before moulting into a 5th instar caterpillar. The old head capsule is translucent and you can see the new head which has formed just above it.

The 5th instar larva is almost totally green, and it's quite a beautiful color. It can reach up to about 4 cm in length. It no longer has even the slightest hint of the white saddle. The second picture again offers a good look at the fake eye spots and how a predator might view the caterpillar in its resting position. It certainly looks a bit mean in that pose!

Many swallowtail species have pupae which can take on different colors depending on the season, often being green in the summer but brown if they are formed during the fall so as to resemble twigs and bark rather than green leaves. Curiously in Papilio glaucus, all the pupae are brown no matter what generation produced them.

These pupae measure just over 3 cm long. If the larva was exposed to warmer temperatures and more daylight during development, the pupa will develop to an adult butterfly which will emerge in about 2 weeks. Otherwise, lower temperatures and shorter days signal to the larva that winter is approaching, and the pupa will go into hibernation (also known as diapause) and emerge the next spring. Below is a newly emerged male Papilio glaucus.

Pictured below are a pair of males (dorsal and ventral) and females (dorsal and ventral). Notice that relative to the male, the females have broader black stripes as well as more blue on the hind wings (usually more blue than this even). Females Eastern Tiger Swallowtails are dimorphic, which means they come in two forms. The pictures below show the regular yellow form, but there is also a form that is nearly totally black except for the submarginal yellow spots. These are known as melanic females and they have a large suffusion of blue on the hind wings, providing a pattern which mimics the distasteful Pipevine Swallowtail (see earlier post). I do not have specimens of this form, but they are common in areas where the Pipevine Swallowtail is also common. Melanic females are not usually found in Papilio canadensis, but extremely rarely an aberration or mutant may occur.

It can be difficult to distinguish Papilio glaucus and canadensis, especially on the wing. Many sources will say that Papilio glaucus tends to have a larger wingspan as well as a deeper yellow color with an orange tint, but these characteristics are quite variable. A more useful and consistent feature is the width of the black band along the anal margin of the hind wing, which is generally less than 50% the width of the anal wing cell in glaucus and broader in canadensis. Additionally, if one looks at the submarginal row of yellow spots on the under surface of the forewings, they are discrete spots or lunules in Papilio glaucus but form a contiguous straight band in Papilio canadensis. In the larval stage, 1st instar caterpillars for Papilio glaucus have a white saddle centrally and perhaps just a bit of white near its rear end, while 1st instar Paplio canadensis larvae have two additional distinct patches of white in addition to the white saddle located at the front and rear. I will have more on these features when I write the entry on the Canadian Tiger Swallowtail. Near the hybridization zone of course, the picture gets complicated with hybrids that show a spectrum of features. To add more confusion, "spring brood" Papilio glaucus (those which hibernated through winter) can have greater anal band widths than individuals which did not hibernate and can resemble Papilio canadensis in other wing characteristics. 

Eurytides marcellus

Eurytides marcellus (Zebra Swallowtail) is one of North America's most stunning butterflies. This species belongs to a group of butterflies that is otherwise tropical in distribution, but for whatever evolutionary reason, this species has managed to carve a niche for itself in the more temperate regions of North America while its relatives have not. It is found in the eastern half of the USA, and very rarely reaches extreme southern Ontario, Canada. Some sources will place this butterfly in the subgenus Neographium, but most sources still use the genus Eurytides.

The larvae of this species feed only on plants from the family Annonaceae, and in North America, the predominant food plant is Asimina triloba (common pawpaw). There are other species of Asimina found in North America, and some of these can also serve as host plants occasionally. For example, in Florida, the larvae of the Zebra Swallowtail will happily feed on Asimina angustifolia (slimleaf pawpaw), Asimina reticulata (netted pawpaw), or Asimina pygmea (dwarf pawpaw). This genus is closely related to the genus Annona, which contains species that produce some commercially important fruit such as the cherimoya and custard apple. However, I am uncertain if the butterfly can also feed on plants from the Annona genus.

Both the food plant and butterfly species are rare where I live, but a few years ago, I lived in Washington DC for a period of time, and was able to locate this species and raised 3 caterpillars on common pawpaw. I also saw this species when I visited Florida recently, but did not raise any from that trip as I didn't have the food plant available to me at that time of year.

The picture above is of a 5th instar caterpillar on common pawpaw. It pupated a couple of days later as I recall.

The pupa is compact and angular, and mimics leaves. The larvae will often pupate on the host plant itself, where as many butterfly species tend to wander away to find shelter. There are two color morphs, green and brown. As with many other swallowtail species that hibernate as pupae, the summer generations tend to form green pupae that develop directly into butterflies, where as brown pupae tend to hibernate, and produce the spring generation the following year. The top photo is a green pupa, and after about 9 days, the butterfly has nearly finished development and can be seen through the pupal casing.

This butterfly emerged the following day, and was a male (top picture). The bottom picture is of the same butterfly, now set as a specimen.

As fortune would have it, I recently located some common pawpaw fruit, and will try to grow some plants from seed. Once they are large enough, I may try my hand at raising this species again and take additional photographs.

The common pawpaw is actually the largest native fruit in North America, but is not well known and is not usually available in grocery stores. They do not ship well, and spoil in a short period of time. There are some places that sell them, and some research is currently being done to try to commercialize the fruit and improve its shelf life. A lot of this work is being done at Kentucky State University, and if I recall correctly, Ohio also has an annual pawpaw festival. The fruit are tropical looking and mature in September/October. When mature, the skin turns from green to yellow, similar to a banana. In fact, pawpaw is sometimes also known as the prairie banana, though it neither grows in prairies nor is it related to bananas. Inside, the pulp is soft and yellow. It's hard to describe the flavor to someone who has not eaten pawpaw, but some say it's a combination of mango and banana. I think it's closer to mango, but the pulp is really soft and not stringy at all.

Inside each pawpaw fruit are usually two rows of brown flat seeds, each about the width of a quarter. I have a bunch of these now, and will try to germinate them next spring. In order for them to germinate optimally, they require several months of cold moist stratification, which basically means you have to keep them cold and moist for a while (can be done in a fridge). The cold treatment breaks the dormancy of the seeds.

The mature tree is pyramidal shaped with large drooping leaves, as shown above.

Papilio troilus troilus

Papilio troilus (Spicebush Swallowtail) is found throughout the eastern half of the US and also ranges into southern Ontario in Canada, reaching as far north as Toronto. Occasionally, this species is seen east of Toronto along the north shore of Lake Ontario. There are two subspecies. Subspecies troilus is found throughout most of its range, and subspecies fakahatcheensis is restricted to the southern tip of Florida. This is likely a relic population from the last ice age, and was only recently described by the late Ron Gatrelle in 2000.

The larvae of this species feed on plants in the Laurel family, mainly spicebush (Lindera benzoin), sassafras (Sassafras albidum), and in the southern parts of its range, red bay (Persea borbonia) along with its close relative, Papilio palamedes (Palamedes Swallowtail). The caterpillars of these two species are very similar and can be difficult to distinguish for the novice. In my area, the dominant food plant is sassafras, and that is where I find most of the ova and larvae. I occasionally find pupa on or near the food plant.

Eggs are cream white and laid singly on the underside of leaves. After several days, a black dot will develop centrally within the egg, which is the head of the small caterpillar inside.

These are 1st instar larvae. Right from the start, these caterpillars build shelters for themselves to hide from predators. They will lay silk strands across the edge of a leaf and use that to pull the leaf upon itself and form a furl. They will rest inside this furl most of the time, and only come out to feed. Recognizing these furls is one of the best ways to find larvae in the wild. Occasionally, caterpillars of other species or even spiders will build similar furls, but after a while, you start to recognize the furls that are characteristic of Papilio troilus.

There are two 2nd instar larvae in this picture. When the caterpillars are small, they are a mottled black and white pattern to mimic bird droppings. This is another way in which they try to fool predators.

This is a 3rd instar larva. In this picture, I have unfurled the furl it was hiding in, and you can see the shimmering silk strands the larva is resting upon. You can also see the beginnings of eye spots, which become more noticeable as the larva grows.

These are newly moulted 4th instar larvae. Again, I have unfolded the furls they were hiding in, and again one can see the silk strands across the leaf. The eye spots can be seen a bit better in these pictures.

This is the 5th instar, or final larval stage before pupation. As with many other swallowtail species, the last instar heralds a dramatic color change. The larvae are now a bright green, and no longer mimics bird droppings. They have two huge fake eye spots to scare away predators. At this stage, the furls made from the edge of a leaf is no longer big enough to conceal them, and often they will fold an entire leaf on itself to form its shelter.

Prior to pupation, it will stop eating and start to change color from green to an a burnt orange. I'm not sure why this happens, as it does make them quite conspicuous. They will also leave their shelter, wander off and usually away from their food plant, and try to find a good spot to pupate. In this above picture, the larva is just starting to turn a bit yellow.

This is what the larva looks like when it has completely changed color. They are quite noticeable crawling on the ground, and this is when most people come across these larvae.

There may be anywhere from two to several generations per year, depending on latitude. The pupae come in two color forms, green and brown, like many other swallowtail species. In most swallowtail butterflies, the green pupae are most common for the summer generations that develop directly into butterflies, while the brown form pupae tend to overwinter and emerge the following spring.

The top two pictures are of the same individual - a female raised this year from a larva. The bottom picture is a wild female nectaring on burdock. The adults are medium to large butterflies that are predominantly black with varying amounts of green-blue on the hind wings. They are thought to mimic the unpalatable Pipevine Swallowtail.

From top to bottom, the above pictures are of males dorsal and ventral, and females dorsal and ventral. The males have more green-blue on the hind wings, where as the females have less extensive but bluer coloring.