Jan. 10, 1999
The new year began with a hard freeze over much of central and north Florida which undoubtably will effect the monarch population as the milkweed throughout the freeze area will have been defoliated and I suspect many of the adult butterflies will have succumbed to the cold as well. Here, due the the fact St. Petersburg is surrounded by the warmer waters of Tampa Bay on the south and east and the Gulf Of Mexico to the west, we reached only 34 degrees and damage was minimal, but inland from the coast, the temperatures were being reported well below freezing.
The flying adults I have seen the past few days are diminished in numbers, but there are survivors here at least and a fair number of larva are alive as well. I have found a few dead larva on the ground (possibly due to causes other than the cold), and although most appear to have weathered the storm, there are considerably fewer in the population than several weeks ago as I have been collecting them and bringing them inside to raise in controlled conditions to reduce the stress on the plants and allow them some respite to recover. The plants had been munched back to the bare stalks over the past several weeks (I also cut them back after they went to seed since there was virtually no foliage remaining) and inspite of the reduced foliage, there are already a number of eggs present on the small leaves and sprouts.
Of the monarch caterpillars collected and raised from the backyard over the holidays, I found that approximately 20% (1 in 5) of the pupa were infested by Tachinid flies. For those readers unfamiliar with this nasty little fly, this species is parasitic and lays its egg (usually 1 or 2, but I have seen as many as four larva emerge and pupate) on the skin of a developing caterpillar. When the egg hatches, the larva (maggot) burrows into the caterpillar and begins consuming the caterpillar from the inside. The fly larva does not damage the caterpillar enough to kill it as the caterpillar develops, but when the caterpillar pupates, the maggot, now larger, accelerates its consumption, and does consume and kill the pupa. When mature, it burrows out of the dead chrysalis and lets itself down to the ground on a silk thread. It forms its pupal case on the ground where the new fly will emerge. These flies look very much like common house flies, perhaps a tiny bit larger. I have a collection of about fifty pupas that have not emerged as flies yet. I won't be releasing them, but I may fly them in an aquarium for a while for observation. At the moment, these Tachinid Flies appear to be the chief predators of the monarch larva. I have also observed a few wasps consuming larva from time to time on particularly warm days, but their impact appears to be minimal at this time of year.
January 28, 1999
The impression I have been getting from a number of monarch enthusiasts I have spoken to over the phone lately is that monarchs are plentiful in the area at the moment since they all complain the about the current leaf depleted state of their milkweed stock. When the plants reach this condition at this time of the year, I will often find the larger caterpillars patiently gnawing the last chewable parts at the top of a plant stalk. At this point, we affectionately refer to them as "chewing on fudgecycles."
I have also observed that as food gets scarce, the caterpillars will become noticably more aggressive toward each other. I have observed that if two of them meet at the top of a stalk, they will battle for the choicest chewing spot, and if equal in size, tend to settle in on a my side/your side kind of compromise. If a third equal size caterpillar shows up, the first two refuse to share any further and drive it away. Two's company, three's a crowd, is a real event in monarch caterpillardom when reduced to eating milkweed bark. No more Mr. Nice Guy. I have also observed while the final instar caterpillars nearly always actively search for food, the smaller caterpillars tend to simply sit tight for a while and wait for the plant to grow a bit of food rather than risk leaving the plant and getting lost or eaten by ants on the ground. The small, early instar caterpillars do not need much of a leaf and the plant's overnight growth will usually meet it's requirements, but for the final instar mature "pig 'pillars," the clock is running and the feed bag is on. They'll eat the bark off the stem if that is all that's left.
I have noticed the Tachinid flies have declined somewhat, in part due to my bringing in the larva and preventing them from multiplying too prolificly. I did reach a count of nearly 100 Tachinid pupa that were not permitted reintroduction into the wild. Yep, they died like flies. However, I have seen a few outside, so they are still around, but they are not infecting nearly the number of caterpillars they were a few weeks ago. Of course, that could easily change. As the plants recover, and as I write they are beginning to green up again, more caterpillars will be forthcoming. I have seen at least two females laying eggs over the last couple of days and there are also many chrysalids in the weeds that have yet to emerge. I see at least one new butterfly every morning now. I have also observed one that could not inflate its wings and another that emerged too small from lack of food (I assume) and unable to fly. I did also find a few caterpillars that had died from unknown causes, probably a bacterial infection, but most appear healthy and have good appetites. Very good appetites.
March 15, 1999
The month of February was fairly uneventful insofar as the Monarchs were concerned. After the initial population explosion, the number of larva seemed to decline to a steadier number as I find several every day, but not enough to completely denude the plants which have greened back up considerably, but are now very much under attack from several hundred thousand (give or take a few) aphids. It has been cool and the lady bugs, although now growing in presence, have not been in sufficient numbers to control the aphids which are exploding in population at the moment. The little hover flies have not been around in any numbers lately either. However, there are lady bug larva and eggs present, and I've found a few hover fly larva, so the aphid's days are numbered, but it may take the predators a generation of two to multiply to genocide level.
There are adult Monarchs flying, but I have seen a noticable reduction in numbers although it is easy to count half a dozen at any one time during the warm part of the day. I have seen a few tachinid flies and found a few dead chrysalis which may be the result of this parasoid. However, I have also observed an occasional dead caterpillar on the ground which may be an indication of disease now in the population.
I finally did determine that the disease problem I experienced last year was possibly not a virus, but a bacterium, Bacillus thuringiensis, which is commonly known as BT and is widely employed as a biological control pesticide. It is always present in the wild and I suspect it was carried to the other leps by the explosion in the eastern tent caterpillar population last summer which did, as I think back, coincide with the other lep problems. I also in reflection note that while I was in a nursery buying a few plants last summer, several people came in looking for something to kill the "worms" in their trees. The eastern tent caterpillars were so abundant, you could not help but walk on them while traveling almost any sidewalk near an oak tree and the frass (we have oaks) fell from the trees in such quantity that it covered the driveway and sounded like a light rainfall during the heat of the day. They are harmless and do not really need controlling, but uninformed people panic when they see so many caterpillars munching their oaks and decide to do something to save their trees (they recover nicely on their own) from being munched to bare branches. I found out later that the nursery owners recommending a brand of BT to kill the caterpillars, so possibly part of the lep problem was, in fact, man made, although there has been no perceptable deep impact to the butterflies as they are all here again this year.
Below is a piece of information I pulled off the net concerning BT. I have left all the credits and disclaimers intact.
________________________________________________________________________________________________________
Michigan State University Extension
1993-98 Landscape CAT Alerts - 73093009
02/12/99
Bacillus whatsit whatsit?? Ed Grafius, Entomology
------------------------------------------------------------------------
What is it?
Bt is an abbreviation for a group of bacteria called
Bacillus thuringiensis. There are many strains or varieties
of Bt and some kill insect pests if consumed. Although Bt
is a bacterium that attacks insect larvae, it does not
usually multiply in the environment and reinfect new hosts
like other diseases and needs to be reapplied regularly
like a standard insecticide. It is commonly found in soil
and its true life cycle is not known.
Until recently there was only one strain of Bt in common
use, Bacillus thuringiensis variety kurstaki. However, many
new strains are being discovered and developed, each with
different pest activity.
How does it act?
Bt products contain crystals produced by the Bt bacterium.
These crystals must be consumed by the insect. They break
down in the insect's gut and release a toxin. The toxin
attaches itself to specific sites on the insect's gut wall
and breaks down the gut wall, letting gut enzymes and
bacteria into the insect's body, eventually causing death.
Feeding by the insect stops within a few hours after a
toxic dose of Bt is eaten and death occurs within 2 to 4
days. Because the Bt requires a specific gut acidity and
environment and specific attachment sites on the gut wall,
each strain of Bt is only toxic to a specific group of
insects. Bt acts primarily against larvae because they
generally feed the most rapidly and some insects, such as
mosquitoes have different adult food sources.
Is it safe?
Bt is harmless to humans, wildlife and even most non-target
insects. It does not affect pollinators such as honey bees
and are not toxic to natural enemies of insect pests. Many
new strains are being discovered and marketed for insect
control. Because of their human and environmental safety,
registration of Bt products is much easier and less costly
than registration of synthetic insecticides. They are safe
for applicators, farm workers and consumers.
What are the different varieties of Bt?
Bacillus thuringiensis var. kurstaki has been used for many
years to control larvae of moths and butterflies
(Lepidoptera). Common brand names are Biobit, Condor,
Cutlass, Dipel, Javelin, and Larvo-Bt (see table). M-Peril
is Bt kurstaki toxin encapsulated in killed Pseudomonas
bacteria to increase residual activity.
Bacillus thuringiensis var. aizawai is a strain of Bt that
is also active against Lepidoptera larvae and may be more
active against diamondback moth than Bt kurstaki. Bt
aizawai is available commercially as Xentari. Agree
contains both Bt aizawai and Bt kurstaki.
Bacillus thuringiensis var. tenebrionis (also called Bt san
diego) is a strain that is active against Colorado potato
beetle larvae and cottonwood leaf beetle larvae. It is
available commercially as Novodor. M-Trak is Bt tenebrionis
encapsulated in killed Pseudomonas bacteria. Foil includes
both Bt tenebrionis and Bt kurstaki.
Bacillus thuringiensis var. israelensis is a strain that is
highly active against mosquito and blackfly larvae. It is
harmless to fish and other aquatic organisms, including
other aquatic insects.
Bacillus thuringiensis Varieties, Brand Names and Pests Controlled
Variety Brand names Pests controlled (larvae)
Btaizawai Xentari, Agree* Lepidoptera, especially diamondback moth
Bt kurstaki Biobit, Condor, Lepidoptera (some species are much more sensitive than others)
Cutlass, Dipel,
Javelin, Larvo-Bt,
M-Peril**, and Agree*
Bt tenebrionis Novodor, M-Trak** Colorado potato and Foil Beetle, cottonwood leaf beetle
Bt israeliensis Bactimos, Skeetal, Mosquitoes, black flies
VectoBac
* includes both Bt aizawai and Bt kurstaki.
** Bt crystals encapsulated in killed Pseudomonas bacteria
(produced by inserting the Bt gene into Pseudomonas,
culturing the Pseudomonas and then heat-killing the
Pseudomonas).
Bt and biotechnology
Bt is being used as a source of resistance factors for
genetically engineered plants. Bt genes and promotors to
activate these genes have been successfully introduced into
several crop plants, including potatoes and cotton.
Genetically engineered potato plants with Bt resistance
factors against Colorado potato beetle have been
experimentally tested in the field since 1991 and may be
available commercially by 1995.
Bt in your future
New strains of Bt will continue to be developed as
insecticides and used for a source of resistance factors in
genetically engineered plants. Because of their
environmental and human safety and compatible with
biological control, they will become common insecticides in
many crops. Use of Bt in place of synthetic insecticides
will increase pesticide applicator and farm worker safety
and make it much easier for growers to meet new strict OSHA
farm worker safety standards related to pesticides.
------------------------------------------------------------------------
This information is for educational purposes only. References to commercial
products or trade names does not imply endorsement by MSU Extension or bias
against those not mentioned. This information becomes public property upon
publication and may be printed verbatim with credit to MSU Extension.
Reprinting cannot be used to endorse or advertise a commercial product or
company. This file was generated from data base C1 on 02/12/99. Data base C1
was last revised on 02/12/99. For more information about this data base or
its contents please contact catalert@msue.msu.edu . Please read our
disclaimer for important information about using our site.
-----------------------------------------------------------------
Good stuff, huh? Ask your nursery if they use BT as an insecticide or the wholesalers they buy from. If you want a butterfly garden, you don't want these little guys hitching a ride home with any of your plants.
April 12, 1999
Spring has finally officially arrived. Two spicebush swallowtail pupa I raised last fall and overwintered in chrysalis (even in Florida, some butterflies, especially swallowtails, overwinter) emerged this week. Also, all winter, a single giant swallowtail would visit each day around noon. Our yard apparently is a favorite on his nectar route and as I have a wild lime planted, I am sure it was a male checking for females as well. Today, however, for the first time, I saw a pair flying. I have also found polydamas swallowtail eggs on the pipewine and there are giant sulphurs present.
Yesterday, while gathering some milkweed for the cats, I almost stepped on a red earred turtle, about a foot in diameter, that was in the middle of the yard. After eyeing me over, she truddled over to my carefully cultivated butterfly garden and, after clearing a few flower seedings out of her way, dug a nest and buried her eggs. It is not a lep story, but it was an interesting sight. I marked the nest so I wouldn't accidently dig there while working the garden.
Insofar as the monarchs, the adults are present in good numbers. I saw several new ones emerge this morning and the caterpillars recently increased in count. I easily pulled in 100 over only few days, but at the moment there are fewer. The lady bugs have just completed their consumption of the aphids, but there are plently of aphid pupa attached to the undersides of the leaves, so this is just the end of round one. I also found there are two different kinds of lady bug larva out there now.
May 4, 1999
The monarch adults are still ever present with egg laying females generally an everyday occurance, but although there are plenty of eggs being deposited, the surviving larva have been steadily in decline and, at the moment, there are really none to be found. There are plenty of small "munchy holes" in the leaves as evidence of their presence, but none appear to reach more than minimal size. I am relatively certain the reason for their disappearance is the increased presence of wasps. I have in fact witnessed them being taken. There are now at least two species of wasps on patrol in the milkweed now.
However, the presence of a disease can not be totally discounted either although diseases in my experience usually do not kill the larva until they are larger. I did receive a post from a newsgroup I belong to concerning the disease (I still suspect it is bacteria) problem of the caterpillars (which indeed did recently break out again in my protected caterpillars in containers) and was noted as "sounds like (symptoms) tree top disease which is a form of polyhedrosis" which is a virus. I have queried many sources about the disease and have an equal number of differing answers. I think I'll simply call it "butterfly bury bury" or maybe "caterpillar keeloveritosis." A common name for polyhedrosis according to what I found on the web is "wilt" because that is what the caterpillars do, they scrunch up and melt.
On the pipevine, there are polydamas swallowtail caterpillars, the first ones of the year, and four have just pupated. Orange barred giant sulphur larva are also present. I found a few mature cloudless giant sulphur larva a couple of weeks ago, but there are none present at the moment. The cassia is peppered with eggs, so I expect to see a momentary increase in the sulph population if the wasps don't get them. There are gulf fritillaries present and a few zebra longwings. A giant swallowtail visits regularly, perhaps more than one, but there are no larva on the wild lime as yet. I have not yet seen any black swallowtails at this writing, but it is still a bit early for swallowtails. Here in Florida, they tend to overwinter as chrysalis just as they do in northern climates.
June 6, 1999
I finally did find giant swallowtail eggs on the wild lime and brought them in to raise. Eight have made it to chrysalis. I returned one caterpillar to the wild lime to hang naturally on the tree. It was interesting to watch the caterpillar roam around, trying out one spot and then another. It finally settled into a crook under a spot where a small limb split into three branches. When it formed it's chrysalis, it blended in to the scene so perfectly, you would only at first glance believe it was simply the short remainder of a broken fourth branch, but in reality, it's a butterfly. If I missed collecting any eggs that were on the tree, none left outside made it to maturity that I could locate. Probably they've fallen prey to the wasps, perhaps birds or lizards, or the ants which protect the small black aphids that appear from time to time on the wild lime and are some present in some numbers now.
There are daily a number of adult monarchs flying and females are present laying eggs, but the larva have not been reaching maturity to my observation, and are apparently falling prey to the ever dilligent patroling wasps. However, a couple of weeks ago, I did find two 5th instar caterpillars. They were grazing my milkweed seedlings and because they were on plants only three inches high (now one inch high) and away from the taller plants by some distance, I suspect the wasps simply missed them. Lucky little fellows. Then, they need a little luck now and again. The wasps are very efficient. I see many leaves with small holes made by 1st or 2nd instar caterpillars, but that is about as far as they get.
White peakcock butterflies have finally appeared in the past few weeks. I sighted several adults flying today.
July 11, 1999
The monarchs are still flying, and, although there are no surviving larva to be found, there are still eggs present, but their numbers are becoming diminshed.
I made a discovery this evening. I have observed many small holes in the leaves where the caterpillars had hatched and began to munch, but never made it past the point in time where they had consumed but a very small part of the leaf. I had thought they were being taken by the wasps, but also wondered why the very large wasps were interested in a hatchling caterpillar which is hardly big enough to make much of a meal.
I had placed a number of hatchling caterpillars on a few plants and have noticed the number of caterpillars growing to larger size were fewer than the number of caterpillars I originally placed on the plants which are protected from wasps on my porch. I know that when the wind blows or you bump the plant, the hatchling caterpillars will drop down on a length of silk as an escape mechanism from predators, but they also, espeially if windy, get lost by either the silk breaking or the caterpillar lower itself to far and misses the plant altogether. At this size, they starve very quickly, in a matter of hours. I had simply surmised a number were meeting their end this way by accident, until tonight.
I was placing a few hatchlings on a plant leaf when I witnessed one of them appear to stand up on end and rollerblade down the leaf. I had never observed this behavior before. They normally crawl along horizontaly, but this one was zipping along standing on end. I acquired my magnifying glass and ventured a look and to my astonishment, the hatchling was being carted off by a very tiny ant less than half the length of the hatchling. The ant is red and is absoultely tiny. As I was observing this one (I scooped him up with a paint brush), a second ant started running off with another hatchling. I quickly captured him also and then scoured the plant capturing a half dozen more of them which I now have in a, ahem, small jar for identification. I had a number of monarch eggs on a piece of paper in a container so I threw a couple of ants in with the eggs (which were hatching, but there were no hatchlings at the moment as I had removed them) just to observe them under the light and I noticed another interesting facet of their behavior. They ran up to a number of eggs and tried to open them. They recognized empty eggs and moved on quickly, but when they found an egg with a live embro, they tried to open it. They were not successful, the egg shell is too tough, but they did know the difference and were definetly after the about to hatch caterpillar and knew it was there. I noticed on the plant the caterpillars that were a day old were already now too large for these ants and witnessed one simply drive one of the ants away with a head bobbing maneuver which means they have a window of only about 24 hours after the caterpillars hatch until they grow too large to successfully attack. I observed this at about 11 p.m. this evening which leads me to believe the ants are nocturnal foragers which is why I hadn't noticed them before outside, but then they are so small, I just may have been overlooking them.
However, when they do grow too large for the ants, they shift from ant food to wasp fodder. At least, that is one small mystery solved. And, with the summer weather, the diseases are also back, too. I've seen several caterpillars I've raised protected sucumb to disease. I've heard other individuals describe the same problems, so it isn't just here, it is a general problem. Even so, with butterflies still in the air, some must be surviving somewhere, but with all the problems, we may see the monarch disappar from the landscape here soon.
August 15, 1999
The monarchs are still flying, a half dozen or so regularly buzzing around, but there are still no surviving larva I have been able to locate although eggs are still present which indicates an active female population is yet in the area. I did find two dead monarch chrysalis, one under a large leaf and the other under the eve of the house which means that a few caterpillars must be maturing, and escaping my (as well as the ant's and wasp's) attention, and also, because they were dead and decomposing, indicates disease is indeed present in the wild and not just in the caterpillars I have been raising inside.
I did observe a pipevine swallowtail flying here over the past few weeks which is the first one I've seen in the garden since it's inception and a welcome site. We usually have polydamas swallowtails laying eggs on our pipevines each summer, and this summer is no exception as we raised and released a number so far this season. Hopefully, we will have a few pipevine swallowtails to add to the population later. I found a clutch of eggs on the surface of a leaf which may be pipevine swallowtail eggs. The polydamas usually lay their eggs directly on the stem of the vine, but the eggs have only just hatched and are too small for me to positively identify at the present. Their appearance is very similar. Eastern black swallowtails and giant swallowtails have also been present as well as their larva which we have brought inside to raise when located. Their survival rate without protection, like the monarchs, is practically nil. Some of the eastern black caterpillars also succumbed to the same disease affecting the monarchs which means the disease is indemic to leps in general and not just monarchs.
Orange barred giant sulphurs and their larva are present, and white peacocks are now present in fair numbers.
September 27, 1999
Since my last entry, the monarchs have been continuously flying here, not in large numbers, but I see one or two females laying eggs and at least three males cruising the patch just about every day. It appears that like last year, they will probably be a continuous presence as the fall migration is now underway and I expect their numbers to increase here shortly with the new blood from up north. The butterflies I see flying are in very good shape which leads me to believe they are locally emerged. There are now a few larva surviving here and there, but only a very few. The wasps are thick now and they make mincemeat of any caterpillars they can locate. Their patrols are relentless, but if a caterpillar is lucky enough to find itself in a shady, remote part of the patch, and the hatchling escapes the ant patrols, it seems to escape notice by the wasps who prefer the sun. However, I can count the observed survivors on one hand over the past weeks, so there are enough surviving to continue the species flying, but only enough. Of course, in nature, that is usually plenty enough.
The cassia, Cassia alata, is in blossom and I have found a few of the yellow and black barred caterpillars of the large orange giant sulphur as well as both cloudless and orange barred giant sulphur caterpillars. The large orange only shows up when the cassia is in blossom and its caterpillars only consume the blossoms and immature seed pods, rarely the leaves. Its camouflage is yellow to match the blossoms while the others are green to blend with the foilage. I often see this caterpillar misidentified in books as the orange barred caterpillar, but it's not.
We have a few giant swallowtail caterpillars and a number of polydamas swallowtails, now in chrysalis, and I have seen a few pipevine swallowtails, but not found any larva. We raised a few eastern blacks, but have not seen any new ones flying in the past few weeks. The white peacocks are also declining and I have not seen many of them either. They tend to move further south for the winter months.
October 12, 1999
Columbus Day. The unofficial arrival date of the great monarch migration to my back yard. There are indeed more monarchs flying now. Whether they are migratory immigrants or native born, who knows, but there are definitely a few more flying now. The larva still are not surviving well. The wasps are still around, but it is now getting cooler and they appear to be becoming less active. We'll see. I've recently collected some Giant Swallowtail eggs and also Polydamas Swallowtails are still fairly abubdant and another generation of caterpillars is present and also Orange Barred Giant Suphurs and their larva are around. I've seen a few White Peackocks also. Strangely, I haven't seen many Gulf Fritillaries this year. They've been around, but not many. I've seen a Pipevine Swallowtail or two this year. Their the first ones I've seen here, but the Polydamas always seem to attack them and drive them away. I've not found any of their caterpillars mixed in with the Polydamas on the pipevines. The visitors may have been males, however.
November 8, 1999
According to the posts I've read on the dplex list at MonarchWatch, the vanguard of the monarch migration has reached some of the sanctuaries in Mexico. This year, by all accounts I've read, appears to be a very good year for monarch numbers. In my backyard, I have counted an average of eight flying everyday and did notice one, a female, was rather threadbare. Her wings were not particularly tattered, but she had lost her luster due to loss of scales and her wings were very nearly transparent. She was resting on one of our bamboo plants when I spotted her in the morning a couple of days ago. I was able to reach over and capture her with my hand easily because she was still cold. I'd seen her flying and observed her laying eggs for a few days after I first saw her, but now I don't see her anymore. She had all the appearance of being a migratory immigrant, but there is no way of actually confirming she was. I've been dilligently watching for tags, but have not found one on any butterfly here yet. Incidently, if anyone who finds this page would like to subscibe the MonarchWatch's dplex list, it is free. Go to: <http://www.monarchwatch.org> and simply follow the instructions to subscribe.
Incidently, there is a very interesting article on monarch butterflies in this month's issue (Nov.) of Vanity Fair magazine. It concerns the interesting political history surrounding the discovery and preservation of the overwintering sites in Mexico. Well worth reading.
The monarch larva, even though there have been a growing number of eggs laid, are still not surviving. The wasps are still on patrol and the ants are still active. I believe the ants are taking most of them as hatchlings, but this morning, I did find two larva that had survived to the second instar, so perhaps things are about to change. It has been getting cooler here day by day.
November 19, 1999
Over the past few days, I've recovered approximately three dozen 5th instar monarch larva. It appears the larva are beginning to survive now in more significant numbers. I've observed an increasing number of monarchs, in particular, females laying eggs. I actually netted all the butterflies (monarchs) I could find and released them elsewhere to check for new arrivals and the yard became populated again in a day or two with a dozen or so more butterflies. There are also giant swallowtails laying eggs yet. I have three caterpillars I recovered as eggs. They haven't been surviving outside due to predation. Some of the cassia is populated by large orange sulphurs and orange barred giant sulphurs. The white peacocks are nowhere to be seen. They tend to move further south in the winter months. I have seen several gulf fritillaries flying lately. They've been strangely absent in any significant numbers this summer. I did also site a smaller yellow butterfly with black edges on its wings. I suspect it is a common sulphur or a relative. They are not a common site here and this one didn't stay long. I still see polydamas swallowtails flying, but I haven't found any caterpillars lately.
November 29, 1999
The monarch caterpillars are surviving, but now that they are, they are also attracting tachinid flies. I found one pupal case today under a dead chrysalis. I have also observed two other pupa outside have died before emergence. It may be disease or the flies, I can't be sure. I had assumed it was disease until I found the tachinid pupa. I have, however, found that disease has taken a few of the caterpillars as I found some dead, but it definitely appears to be much less impactive now than earlier. The disease seems to appear in the spring and begin to disappear at around this time. At least, that is what it did last year. It seems the cool, dry winter climate here is not favorable to the development of the disease, but as we return to our tropical climate, it comes roaring back. December through March is appears to be the clearest period which is good for the monarch butterflies. That is when they produce their highest numbers with the immigration of the northern stock in addition to what may be flying here as residents. We have not had a hard freeze here in a couple of years and the winters have been relatively mild. I will be interested in seeing if a hard freeze (when we get one, which is inevitable at some point in time) influences the disease situation.
The milkweed is just now beginning to flower. I think they know what is about to happen to them. It's time to produce seeds and bail out before the monarch winter buzzsaw hits.
December 15, 1999
The monarch larva are surviving in larger and larger numbers. I easily counted 100 5th instar this week. Merry Christmas.
We will post further observations as warranted.
Thanks for visiting.
Dale & Peggy McClung
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