January 8, 2003
I happened to have some tags on hand from Monarch Watch, so this fall, I decided to tag the fall arrivals. The first was tagged 10/24, a male in fair condition, and I recovered this male again on 10/30 and again on 11/8. The first tagged female was 10/25. In all. I tagged 8 females from 10/25 to 12/10, and 7 males from 10/24 to 11/28. I observed two of the tagged males mating with females during this time, but was unable to capture either pair (too high in a tree). All the females were captured in the process of egg laying in the morning. Two recaptured males, one from 10/24 to 11/8 and another from 11/10 to 11/28, appeared to take up residency. The longest period for a female recapture was 10/28 to 10/30. The females appeared to stay a day or two universally and then move on. The total tagged was 15 with the last tagged 12/10. Since then, I have not seen any new monarchs in my backyard.
I did recover over 50 larva from the plants either started from eggs collected or as larva at various stages of development.
The fall wave of monarchs seems to have passed by. There are no adults flying. Giant sulphurs are around and a few gulf fritillaries, but that is all I see. I did recover three 5th instar larva the past few days and I have seen at least one smaller caterpillar, but the population explosion of earlier weeks has subsided.
February 14, 2003
I did not see an adult monarch flying until Jan. 9, a female. A second female appeared the following day, but since sightings have been few, a couple more single monarchs, all females, but one female did show up yesterday. The larva have been present, but in smaller numbers as one may expect, a couple of dozen found, but the milkweed plants are freeze damaged and foliage is sparse. The weather has been unseasonably cold for our locale in Florida. Our normal high temperatures have averaged 5-6 degrees below the norm of 70, 65 or so, but many days were even cooler and we dropped below 32 on a few nights, rare for us. Now it is beginning to warm again. Valentines Day, February 14, is usually the time when we may begin to relax from freezes or frosts here. Late February is planting time.
This has been an El Nino year and that has played havoc with the weather. Our summer was overly hot, setting some records, and our winter overly cold, setting some other records. The one positive point about El Nino years is we do see an increase in rainfall and that has been welcome, but now we are into our full dry season and rains are sporadic at best.
Giant sulphurs have been present all winter, both the cloudless and orange barred, and I have collected a dozen or so small larva on some of my potted cassias this week. Gulf fritillaries are also around.
March 14, 2003
Adult monarchs have been noticeably scarce this spring thus far, but have been consistently around in small numbers, two or three sightings a day, few males. However, larva have been present the whole time and in some numbers. I collected twenty a week ago that are pupa now. I have collected another two dozen or so since then. All have been fifth instar when taken from the plantings. The monarch pupa, thus far this spring, have been healthy with good emergence of healthy adults, but I am now beginning to recognize some of the early symptoms of what I have called "the Florida malady."
For those that may visit here and read this humble chronicle, to recap some, "the Florida malady" is a situational problem concerning the monarch butterfly when reared on tropical milkweed, Asclepias curassavica, also known as scarlet milkweed, butterfly weed, Mexican milkweed, and possibly some other names I am unaware of. South of the southern limit of common milkweed, Asclepias Syriaca, which is somewhere in mid Georgia, we are limited to this species of plant for the most part . There are other milkweeds, but tropical milkweed is the more commercially viable species, it has attractive flowers and may be grown relatively quickly from seed or cuttings. It is the most common species sold for butterfly gardens, usually the first larval host purchased (everybody loves monarchs), and over the years has been so introduced into the Florida landscape by garden clubs, butterfly clubs and organizations, not to mention grown by county and state for habitat introduction in parks and preserves, that it has been termed "naturalized." A. curassavica is also the primary species used by commercial butterfly farms in the southern states for growing monarch butterflies.
Tropical milkweed is not a native plant on the Florida peninsula, it occurs naturally in Mexico and the Caribbean. It is known to be more toxic than the common milkweed of the temperate region. Common milkweed is mild enough to be considered an edible plant. Tropical milkweed is ranked with the poisonous plant species.
The malady is that in the spring, notably when the daytime high temperatures begin to break 80 degrees f., the larva begin to die. In the late fall, when the temperatures drop below 80, they begin to recover and remain healthy through the winter months for the most part. There are always other variables, other pathogens to contend with, but their survival rate is always dramatically higher in January as opposed to June, and it doesn't seem to matter what methods concerning hygiene in rearing are implemented, the malady is still there. It follows a natural, seasonal pattern.
The first noticeable symptoms are greenish or reddish discharges from the larva which will, in relatively healthy or non lethally effected larva, discolor the silk button, usually in a reddish tone, as they spin in preparation to pupate. The frass will also take on a reddish cast. The malady's onset is gradual. As the butterflies emerging from their pupa, a few at the start, then in increasing percentages, week by week, depreciate in health in increasing numbers until the mortality reaches near absolute. Most that emerge are wet, a healthy monarch should be powder dry, and may stick in the chrysalis (also a symptom of parasites), or if they do emerge successfully, may be undersized, poorly marked either on the wings or, more commonly, lack clear white markings on the abdomen. The abdomen may be completely barren of scales.
As some time passes, the point of death backs up into the developmental instars of the larva. The larva may successfully hang, but die when molting. As it progresses, the molt from 4th to 5th instar will also become a point of noticeably increased mortality, but most commonly, death occurs in the 5th instar.
The first symptom is the larva stop eating, and for those of you that have raised any monarchs, you know how much they will eat normally. My nickname for 5th instar monarch caterpillars is "pig pillar." From the 1st to the 4th instar, they consume but a few leaves. They double their size everyday when not molting at which time they stop and rest. When they reach the 5th instar, they will still double their size daily and since they are that much larger, their consumption dramatically increases. The next molt is to pupate and they will consume as much as they are able until the onset of metamorphosis which begins with internal changes within the larva. At this point, they naturally cease feeding and seek a protected location to pupate.
On a plant, 5th instar larva exhibit a behavior where they will partially sever the leaf to restrict the flow of sap into the leaf and then crawl down to the leaf tip and feed upside down, coincidentally employing the leaf also as a convenient camouflage, a blind concealing their location from patrolling predators like wasps. This natural behavior is considered to be a conscious attempt to restrict the toxic latex sap's flow to lessen the toxicity produced by the plant of the particular leaf by cutting the pipeline. I have also observed 5th instar Queen larva completely top the plant and fall with the top to the ground where they will feed.
When the monarchs initially begin to show signs of reduced or loss of appetite and cease to feed, I have noticed it seems, to my observation, they appear to my untrained eye to be losing their ability to recognize the plant as food. Caterpillars taste with their true feet, the six true legs behind the head of the caterpillar, just as adult butterflies have their taste receptors on their feet. A problem larva may nibble a bit, then quit and move on, nibbling here and there, but not consuming the whole leaf (which is the normally what they will do once they've begun consuming the leaf), and eventually, not feeding at all. They seem to be unable to recognize the plant. A healthy caterpillar, if placed in a container with a leaf, will begin feeding usually as soon as it's true feet come into contact with it. A malady larva will run around and around as if it is seeking food, but does not appear to be able to recognize the chemical signature of the plant material. It acts hungry, but doesn't eat. It runs over and over the food leaves and pays them no attention.
As the larva become more directly effected, they begin to lose fluid through anal discharges, notably a green color initially changing to red near the end. They will not pupate, but die as larva. Caterpillar-keel-over-it-o-sis.
This is all speculation based upon observation. I have been wrong about things before, but the best correlation relating to the mortality problem is, aside from the weather and climate change, the growing cycle of A. curassavica. In the winter, when the plant produces seed pods and is also more dormant, growing slowly, the larva thrive. In the summer, when the plants are growing at their peak rate, not so good.
Well, I'm still working on an exact answer. I don't have one yet, but it is not a situation unique to my location. Over the years, I have known of many other losses by hobbyist and butterfly farmer alike I am in communication with. The common thread that runs through the group is tropical milkweed. In the north, this is rarely a problem with larva raised on common milkweed except under conditions of extreme heat and humidity in late summer which is probably more of a hygiene problem. If this were a problem associated with only my own butterfly raising, I would not document this, but it occurs regularly in many locations in the south. Most blame diseases. I am no longer so sure it is completely a disease problem.
The free flying monarchs are still not up to squadron strength yet.
March 17, 2003
Some of the swallowtail species are beginning to show up now, notably giant swallowtails. I did see my first polydamas swallowtail today. The giant sulphurs have been doing well all year and gulf fritillaries are a daily sight with larva on the passion vine, notably P. Incense and P. suberosa.
Over the past few days, I have recovered another two dozen or so nearly full grown monarch larva and, surprisingly, six queen larva. I did not see a queen. She must have slipped in and out without my notice, but her young are here.
The adult monarchs, it seems quite suddenly, are up to squadron strength again with several males showing up and forming territories. The first monarch from the previous collection emerged this morning at about 10:30 a.m. and was larger and healthy. She formed her pupa on March 7, 10 days to emerge. Evidently, the malady isn't here totally yet, but the temps are rising.
March 20, 2003
This year is an El Nino year which, for Florida, has delivered a bit warmer past summer followed by a cooler and wetter winter. While the warmer summer was less than favorable for the monarchs here in St. Petersburg, observable numbers of adults flying appeared relatively low compared to previous years, the cooler winter appears to have been more favorable, probably producing a very large number of monarchs through the winter breeding season.
I did discover two interesting weather statistics while working on my observations. A weather reporter on one of the local TV stations a while back announced that from April 7 to October 15, at no time did the daily low temperature drop below 60 degrees, 194 days, a new record. Concerning the viability of the monarch larva over the years, I have noted that when the highs break 80 degrees in the spring, their health begins to deteriorate, and when the highs drop below 80 degrees in the fall, they begin to recover. After discovering this statistic, I decided to concentrate on observing the larva in relation to the low temps as opposed to the highs.
This winter, the reports have stated we have been, on average, 5 to 6 degrees cooler than normal. This may not seem like a great deal, but I began to notice this did change the feeding larva's development time, they did take longer to develop as they fed for fewer hours each day. If the temperature was 50 f. or lower, they did not feed at all, at 55 f. they would begin to move, but would not feed but slowly or exhibit normal or rapid movement until the temp crossed the 60 degree f. mark. These cooler temps also effect the plants. Here in FL we are limited for the most part to tropical milkweed, A. curassavica, and I suspect the problem we experience here during the summer may be the toxicology of this species of milkweed as larval survival positively correlates with the growing season. The evidence thus far is circumstantial, but I now suspect what many people consider disease with monarch larva here in summer is perhaps actually toxic poisoning.
The cooler temperatures have also reduced predator activity. In fact, around here, the monarch qualified as a crop pest. My stands of milkweed are munched to bare stems and when they begin to recover, producing new sprouts, there are eggs present on the starter leaves.
I site these observations in consideration that perhaps an El Nino year is perhaps predictably a more favorable year for the monarch. In Florida, below the freeze line, it seems to produce a more favorable a climate considering the number of larva present and their relative health. Considering the recovery of the temperate population this year from last year's die offs in MX, perhaps some similar weather statistic comparisons for the weather in the north may be found.
April 2, 2003
The polydamas swallowtail chrysalis I have had since last fall are emerging, and I have observed adults flying and found small larva on the pipevine. I have seen a few giant swallowtails and recovered one larva from a hercules club. It is currently 5th instar. I am also seeing giant sulphurs, zebra longwings and many gulf fritillaries. The gulfs are producing larva in relatively large numbers compared to the past years, but also, I do have more passion vine than ever before.
There are a good number of monarch adults flying each day, but the milkweed stands are very sparse with foliage, although there are eggs always present there is not much left to support any larva. I am trying to raise a handful on white vine. They do not like the plant as well, but are feeding on it.
May 24, 2003
The last wild monarch larva emerged from its pupa on May 22, formed May 13. The egg was probably laid in late April. Although there are always adults flying, territorial males as well as regular sightings of gravid females laying eggs, no caterpillars are surviving to maturity now. I have, from time to time, spotted a red admiral and finally a white peacock. Polydamas and giant swallowtails are around, but I have only seen a single eastern black swallowtail all spring. Gulf fritillaries abound and there are zebra longwings, three or four, fluttering around in the shadows most days as well as a number of skippers and other smaller butterflies.
August 4, 2003
It has been a while, but nothing has changed except that, at least for my backyard, this appears to be a good year for butterflies in general. The "Florida Malady" has, on cue, returned with regards to monarchs sadly enough. Monarch adults are ever present and there are always (to date) eggs present, but the larva do not survive, not because of the"malady," but because they are taken as prey by wasps and other critters, ants and assassin bugs to name two, before they are able to mature.
October 11, 2003
Tomorrow is Columbus Day, October 12, the traditional day for the monarch butterfly migration moving south from the north reaches my back yard. I'll be looking for tags.
September was a good month for the monarch larva I've been hand raising. The weather was dryer than normal, perhaps a positive indication of a relationship with humidity, but I have a number of times raised many larva in air conditioning with temperatures at about 72-75 degrees without success in the spring and summer. There is more to it in totality I am afraid. However, it was good to see the butterflies emerging in good shape for a change, about 75% appear very healthy and are full size. Outside, however, there are as yet no surviving larva. The predators are still active.
The milkweed plants have aphids on them, but both lady bug and hover fly larva are present and the aphid numbers are low. In fact, the aphids never did grow to any sizable population this summer. I apparently now have established lady bug and hover fly populations of some degree, at least for this season, as the aphids have been around, but never get to any numbers.
Adult monarchs are still a constant sight, but only a few are here presently. I did see a giant swallowtail yesterday, and I have seen a number of long tailed skippers as well. Gulf fritillaries are in low number right now. I see one occasionally. White peacocks are also now a rarity, but there is one zebra longwing flying.
There were four zebras flying at one point earlier this summer. There was at least one female and I gathered and raised some of the eggs as I could find them. I raised a dozen and from them have raised four dozen which are now just emerging adults. The one lone zebra is one, I think, of the original four, probably a male hoping to attract another female. He is over a month old if he is.
Both the orange barred giant sulphur and the cloudless are present. I raised both of their larva from collected eggs which are now pupa. I also have eastern black swallowtail larva from collected eggs. I expect this to be the final generation for the season and the swallowtail pupa should s overwinter, but you never can be sure with swallowtails. This time of year they are unpredicable.
December 6, 2003
Today, I found two 5th instar and also a pair of 4th instar monarch larva. The surviving monarch larva numbers have been increasing for several weeks now. The weather has turned cooler. The last group of larva I raised in captivity emerging as adults this past week and was, for the most part; still some casualties, in good shape, and although a number were undersized, over half were full sized. Ironically, the temps dipped below the 80 degree mark consistently not long ago. The previous brood of larva did not make it, but it was raised earlier in the fall when it was considerably warmer, mid eighties, low nineties. Why am I not surprised?
There are three adult monarch males now in residence. The wave of the migration must have passed here about a month ago, late October/early November. Then, I did find a number of females laying eggs present producing the larva I did locate and collect, but now they are scarce, but I am finding eggs daily, so there must be females in the area, just out of sight.
This is a bit of a quirky observation, but I am going to put it in because I initially found it strange. I planted a small seed bed of milkweed in two rows. The plants had reached about two inches high and needed thinning or transplanting. They were crowded. I should have worked on the bed when I thought of it, but there was no immediate rush as the plants were still very small, and when I returned to begin the task, I found one half of the bed was bare, mown down by a marauding caterpillar. Interestingly, it chewed its way down one row about half way, made a U-turn, and chewed its way to an exit at the same end of the bed eliminating that half of the second row in the process. I now have two short rows instead of two rows twice as long.
Why the U-turn? Caterpillars have very rudimentary eyesight, hardly what we consider eyesight at all. They can detect light and dark and that is about it. However, instinctively, they tend, I have noticed, to move toward light. This is an observation I have made in rearing. I will put a larva on the shadow side of a plant because it will always migrate toward the lighted side. The U-turn probably occurred at noon. The seed bed runs east and west facing south. When the sun moved behind the larva, it changed direction. Still, I'll bet the little fellow ate 200 seedlings before making its escape. Well, now we will see if milkweed seedlings are able to recover from such a munch down.
We will post further observations as warranted.
St. Petersburg, FL
Thanks for visiting.
Dale & Peggy McClung