Staten Island, New York, where I live, is home to half-a-million people crammed into 68-square miles of real estate. The island is criss-crossed by major highways, bounded to the south by the Atlantic Ocean, to the east by New York Harbor, and is separated from New Jersey by one of the most heavily industrialized waterways on Earth. A ceaseless building boom has tripled the Island's population over the past 40 years.

Nevertheless, Staten Island remains the most heavily wooded of New York City's five boroughs, and is home to at least four Saturniidae species. Polyphemus and promethea are abundant, and my hand-reared females nearly always lure wild mates to the breeding cage. Luna and cecropia are less common, but a few wild pairings each season are generally assured. Last summer, for the first time, a wild cynthia male visited a female at my breeding cage.

The inevitable result of all these couplings? TOO MANY fertilized eggs -- with ravenous larvae sure to follow. I typically release gravid females shortly after the male has departed. Still, I'm usually left with more eggs than I can handle. Earlier this season, a polyphemus, bursting with ova, deposited 197 eggs before I could release her into a nearby park! And while this female was exceptional, I generally harvest 50 - 75 eggs per female of each species.

To reduce their number to a manageable level (8-14 caterpillars per brood), I "seed" larvae, in all instars, throughout Staten Island parks and woodlots. This avoids the problem of overcrowding, lessens the chance for disease, and allows some time for work and family rather than gathering foliage all day.

Whether seeding larvae enhances local populations of giant silkmoths remains to be seen. But I think it's unlikely. I have, however, developed some techniques for dispersing larvae, and gathered some data concerning survival rates, and health and development of seeded larvae that I've continued to monitor.

I also retrieve some caterpillars at a later date, usually early in fifth instar, and have noticed a consistent difference in the behavior between retrieved larvae and their hand-reared siblings.

What follows are some tips for anyone wishing to seed larvae, as well as some observations that might be of interest.

SEEDING LARVAE

"Tools of the trade." Very simple, really. A small watercolor brush for releasing hatchlings, as well as a sealable container to keep larvae of any size from escaping en route. For caterpillars in second instar and beyond, the essential tool is a ready supply of green twist-ties you can purchase at any hardware or gardening store.

Where to seed larvae? This depends on the particular species and your own location. On Staten Island, I can seed polyphemus in neighborhood parks. All have abundant pin oak, or other common hosts, on which I rear my larvae. More importantly, polyphemus adults are not known to mate with siblings. So there is little concern that surviving larvae will yield males that may return to mate with their caged sisters.

Promethea, luna and cecropia, however, will readily mate with siblings. So I venture farther afield to seed their excess larvae. I don't feel I have to travel too far with promethea, given their abundance throughout Staten Island. Luna are safe to release in parks about 3 to 5 miles away, where there is ample sweetgum and birch (my usual luna hosts). Conceivably, an adult male luna could make its way to my breeding cage. But it would have to cross many busy intersections and a dizzying array of street and store lighting on the way to my house. Lighting is thought to be of particular disctraction to lunas.

Cecropias are another story. I release them as far away from my home as I can, usually in wooded parks on the other side of Staten Island.

I follow the same procedure when releasing adult moths -- again, to limit the likelihood of inbreeding.

How to seed larvae? I release hatchlings by gently picking them up with the paint brush and tranferring them to host foliage, one at a time. With older larvae, already established on the foliage in a terrarium, I take the whole "sprig" (that is, a live, cut twig on which larvae are feeding) and fasten it lengthwise to a twig on the host tree with one or two green twist ties. I've cut these ties beforehand into 4 or 5" strips. I generally choose a spot on the host tree that will not be easily detected by curious passers-by or nosey park rangers. The green twist-ties help camouflage the sprig of larvae.

How many larvae to seed? I usually release 6 to 12 larvae per host tree or shrub. There's no magic number, but I don't want to overdo it, given the chance that enough surviving larvae might defoliate whole sections of the host.

When I've got a bumper crop of excess larvae, I release them in more than one location, sometimes miles apart from one another. One broiling summer day, three years ago, I released over 500 polyphemus larvae in six different parks on Staten Island. It took four hours, which taught me the value of releasing gravid females the same night they begin depositing eggs!

When to seed larvae? While I have released caterpillars in all instars, I avoid seeding them while they are preparing to molt. It's best not to disturb larvae during this vulnerable period. Also, I typically wait a day or two after molt -- as some larvae, especially in later instars, don't regain full appetites for awhile.

Two of three days later, while gathering foliage for my hand-reared broods, I check on the released larvae. Often, I can't remember where the larvae are, but eventually the sprig of now-dead leaves is a give-away. I examine the surrounding foliage to see how many larvae I can spot. Where possible, I will continue to monitor these larvae throughout the season, making note of development, disease or disappearance.

SURVIVAL RATES OF SEEDES LARVAE.

Hatchlings:

Frankly, the release of hatchlings is akin to setting out bird food. Or meals for other insects. But if you've got 100 excess hatchlings, it's best to release some of them on the first day.

I suspect that survival of these hatchlings is very small -- no better, and possibly worse, than had their eggs been laid in the wild. Gravid females instinctively know the most suitable hosts, and probably have an innate sense of where best to deposit eggs on a particular host to insure survival of enough offspring. For instance, David L. Wagner writes, in Caterpillars of Eastern North America: "The Promethea is a creature of the understory, both as a caterpillar and adult. In contrast, it is not easy to locate Tulip-tree caterpillars because many are high above the ground."

Unfortunately, my physical reach is somewhat limited, and I may well be condemning many hatchlings to certain death depending on where I place them.

Most hatchlings I've released quickly vanish from view (promethea and other gregarious species, which feed in herds, are the exception here). I have observed young cecropia and polyphemus larvae, having settled on a particular leaf, die out over the course of a few days. In more than one instance, it appears that hatchlings have been attacked by ants for invading their turf. The ants bite or sting the larvae, which quickly shrivel and die, but do not carry them back to the colony. Instead, the tiny cadavers remain stuck to the leaf until the next rain.

But some hatchlings DO survive. I am currently monitoring a polyphemus larva, one of four released on our backyard birch tree on the day they hatched. It is mid-way through fifth instar and appears free of disease.

Second-through-fourth instar:

Survival rate increases with the age of the seeded larvae -- though, in second instar, they remain quite vulnerable to predation. After passage to third instar, larvae have a pretty good chance of survival -- perhaps up to 25%. For the most part, polyphemus, cecropia and cynthia larvae don't move far away from the release point at that stage and are easy to observe. Luna, on the other hand, retain a certain wanderlust throughout their development. On my backyard birch, where I have seeded luna as well as polyphemus, surviving luna are likely to reappear on the opposite side of the tree.

Fifth instar:

I only release nearly mature larvae if they are exhibiting "strange" behavior that may be indicative of disease. I recently released a fifth-instar cecropia that had ceased to eat for nearly two days without purging and starting to spin its cocoon. One of it siblings had earlier exhibited the same behavior before getting sick. The point was to reduce the possibility of disease spreading to other hand-reared larvae that were still feeding.

GENDER SELECTION?

One intriguing aspect of seeding larvae may be an ability to achieve a bias in gender among hand-reared larvae. While I would need many years to test this theory, on thousands of larvae, it appears that seeding smaller caterpillars, while keeping the larger ones, will result in a higher percentage of female adults. If true, this can only be done from third through fifth instar, when size differences become obvious.

I'm naturally inclined to seed smaller larvae rather than large ones -- if for no other reason than suspecting "bigger means healthier." I like to keep the biggies! The results, if not coincidetal, could be revealing:

Cecropia. 2007: 13 eclosures. (62% female)
Cecropia .2006: 13 eclosures. (46% female)
Promethea. 2007: 8 eclosures. (63% female)
Polyphemus. 2006: 24 eclosures. (75% female)
Cynthia. 2006: 18 eclosures. (72% female)
Regalis. 2005: 8 pupations. (50% female)

I did not list 2006 lunas or promethea, or 2007 polyphemus, because I only reared 4-6 larvae of each species to adulthood -- too small a sample. But they, too, produced more females than males.

RETRIEVING LARVAE.

On occasion, I retrieve seeded larvae that are in fifth instar. This has included luna and polyphemus on birch, cecropia on wild black cherry and black alder, and cynthia on ailanthus. Curiously, I have never encountered a seeded promethea larva beyond early fourth instar, and have yet to find a promethea cocoon locally -- despite their obvious abundance. Such cocoons were easy to spot on cherry and sassafras along roadsides when I lived in West Virginia. (But I had better eyesight way back then!)

Once retrieved, I isolate the larvae in their own terrarium -- to be sure they are disease-free.

On average, retrieved larvae are a week to ten days behind in development. Some of the reasons hand-reared larvae develop faster in terrarum settings are obvious: A more constant temperature and humidity; no interruptions due to rain; and no predators.

As for rain, I have observed seeded larvae remain perfectly still as the precipitation rolls off them. And prolonged periods of rain can markedly slow development in seeded or wild larvae -- not to mention putting them at greater risk for disease.

My hand-reared broods, safe from the vagaries of the weather, feed heartily in captivity. They are truly pampered. I've noted my regalis feeding throughout the day BEFORE they've passed to second instar. As Bill Oehlke points out, Citheronia regalis spend most of their larvaehood as nocturnal feeders. My regalis, on the other hand, merely "nap" between meals.

There is a practical reason for retrieving a few seeded larvae. As larvae develop more quickly in the terrarium, they can wind up out-of-synch with their wild counterparts. This can pose a pairing challenge, especially for double-brooded species on Staten Island, such as luna and polyphemus. Local luna populations are sporadic, and hand-reared larvae may yield adults prematurely, with no wild males available for mating. Polyphemus face the opposite challenge. Their abundance has resulted in late- August pairings between hand-reared females and wild males. That means a third brood of larvae surviving well into October, and hopes by the breeder that there will not be an early frost!

BEHAVIORAL DISTINCTIONS BETWEEN HAND-REARED AND RETRIEVED LARVAE.

After four seasons of seeding and retrieving Saturniidae larvae, I have noticed that hand-rearing alters behavior. I've already mentioned that regalis reared in a terrarium will quickly begin feeding around the clock. It's possible that indoor lighting -- from ceiling fluorescent lights, when on, and sunlight filtering through windows -- creates a more generally muted light environment. The lack of direct sunlight might trigger the feeding impulse among regalis larvae, and other species as well.

But I'm convinced there's another factor that greatly influences the behavior of hand-reared larvae: the absence of predators. Seeded larvae that I have monitored outdoors, as well as retrieved larvae, spend much of their time keeping absolutely still in order to avoid detection by predators.

Retrieved larvae are so sensitive to vibration that merely toughing the tank, let alone changing foliage, will cause fifth instar larvae to freeze, and stay frozen, for five or ten minutes. Even footsteps in the rearing-room, if too close to the terrarium, will elicit this reaction.

By contrast, fifth-instar larvae that have spent their entire lives indoors will continue gobbling away while I'm cleaning tanks and changing foliage. I can hold a half-eaten sprig of sweetgum in front of my face, with hand-reared luna or regalis attached, and watch the larvae chew contentedly. Retrieved larvae, however, quickly revert to their wild state, and will wait until the commotion has passed before they resume feeding. The result is that retrieved larvae, eating less frequently, will extend their final instar by several days -- in line with normal development in the wild. At this stage, the pampering they receive indoors will make no difference.

In summation, hand-reared larvae will adapt to the pampered indoor life -- and not just in response to uniform temperatures and humidity. What remains a mystery is how these larvae "learn" to differentiate between human breeder and predator? In early instars, hand-reared larvae freeze just as they do in the wild when the terrarium is disturbed. Clearly, wild larvae need to avoid detection by predators throughout all instars. Keeping still, when a branch is rattled by a bird or small mammal, increases their natural camouflage -- and chances of survival.

Curiously, I have observed seeded larvae, in latter instars, continue feeding during a stiff breeze. But gently grab the branch on which they're feeding, and they will stop. Some larvae, in an instant, will raise their heads in a freeze/fright pose; others will instantly stop chewing, the leaf stuck between their mandibles. How larvae can distinguish between a breeze and a predator is anyone's guess. But hand-reared larvae may not be able to distinguish between a breeze and a breeder.

END OF ARTICLE.

Many thanks to Taylor for his well written and interesting article. Several members release paired females after obtaining a small complement of eggs. Females will lay eggs, usually in a frenzy, once they start, so if you have bagged a female for egg laying, you might want to check her every few minutes after dark so you can release her after she has provided the number of eggs you wish to retain.

I very much admire Taylor's patience and concern for the welfare of the larvae. It would be a mistake to release large numbers on a single tree. He has noted, however, that seeding is probably most successful during and after third instar, and properly done, it does require considerable time and effort.

I would tend to suppress the release of any larvae that are showing signs of distress. Rather than release them or isolate them, I would tend to flush them down the toilet. Some of the pathogens they can release through frass or during decomposition may survive over the winter on host plants or on the ground. Neither your other reared stock nor wild populations need any additional exposure to pathogens.

Taylor only reports release of naturally occuring species. I strongly discourage seeding of any species that are not already indigenous to your area.

I tend to think that such releases, especially in the later instars can have a short term effect on local population numbers, but agree, that in the long term a positive result is "unlikely". The best way to increase Saturniidae numbers is to provide additional suitable habitat.

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