Welcome To Our Backyard 2004

Most Recent Observation

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March 5, 2004

Monarch larva have been continuously present since early December and in January and February, true to form, the numbers of surviving larva escalated to what amounts to a population explosion, over grazing the milkweeds. I am still finding some larva, but only one or two at a time and it has been getting warmer. I have seen two species of wasps in the past few days hunting. They are absent during the winter. Now that they're about, survival to maturity will become less sure. The wasps may be the Monarch's enemy, but the for the milkweed, they are a friend. If there is a northward movement out of Florida in the Spring, a migration, it should begin in Mid March in my location here in St. Petersburg.

Adult Monarchs have been present all winter, but in small numbers. I only see two or three normally, but there are both males and females. I am finding eggs.

I have seen Red Admirals about recently, and I observed my first Swallowtails, one a male Giant, the other was Black, but at a distance I could not identify the exact species. Orange Barred Giant Sulphurs are common, and the Gulf Fritllaries have finally shown up, I am seeing two at a time now.

May 21, 2004

This has been an interesting spring for monarchs. Until just recently, I have found 5th instar larva surviving, fewer and fewer all the time, but still there they are. Now, however, I am finding none. The wasps are in full pursuit. The winter here has been cooler, in fact, down right colder, than our normal winter and a bit wetter, more rainfall, than our normal dry season, and that seems to have benefited the monarchs. This has been a bumper year for them, at least, in my locale.

As some who have followed this little column have read, monarchs here demonstrate a predicable decline in the spring, notably when the daytime high temps cross eighty degrees, I have termed the "Florida Malady" for the lack of a proper pinpoint diagnosis. For more info, see previous years. I am only going to note here that three or four weeks ago I was not being very careful and swiped a small amount of the latex sap from the milkweed in my eye and suffered a nasty allergic reaction. There is a chemical change in the plant, Tropical milkweed also known as Scarlet milkweed among other names (A. curassavica), I believe is responsible for the malady. Unfortunately, the only instrument I have available to note this problem change in chemistry is ... umm ... me. The plants can be handled without problem through the winter, but when the growing season gets going, they become more toxic, at least as far as generating a very uncomfortable reaction if the sap gets in my eyes through wiping my brow or rubbing my eye with even a trace of sap on my hand. At the same time, one of my friends in the Orlando area developed the same problem, his worse than mine. I only managed to zap my right eye, he got both of his.

Both of our stocks of monarch butterflies, which had been doing well, began to decline in health thereafter . The pupa that formed during the period of May 10 through 14 are, for the most part, emerging healthy, though there were casualties among them, probably about 20% mortality. Most of the casualty pupa simply died and a few of the emerging adults exhibit problems as well. Those that pupated after are less and less healthy and have declined in size, many are small. I expect mortality in these pupa to be much higher.

June 10, 2004

The last wild monarch butterfly pupa emerged as a normal butterfly on May 29th. It was a loner. I only found the one 5th instar larva. Since, there have been no surviving larva although females have been present and laying eggs. The wasps and ants are the most likely cause of their demise. As it has become warmer, and after predictably dealing with the "malady" problem, I ran some experiments. I have experienced some success in keeping the larva and pupa healthy in the control group, but in the wild group, losses have been nearly universal. I am trying, as I write, to refine the method.

Adult monarchs are always present, but in smaller numbers now. Two or three at a time.

July 28, 2004

While monarch adults have been present all summer, several, both males and females, are flying in the yard now, no surviving larva have been found reaching maturity. I have found some 1st or 2nd instar larva, but they do not last long. Between the wasps, the ants, and the other wayward critters (I have seen a number of assassin bugs this season also), it has been a clean sweep.

Over the years, with the plantings, especially the larval hosts which provide caterpillars, a prey item, as they are, in the absence of pesticides, the predator populations have also become established. I hardly concern myself now with aphids. The lady bug population is residential now, and because I provide them with aphids, they increase in number and I am sure probably expand out into the neighborhood hopefully benefiting others.

There is a natural rhythm. The monarch larva surviving in the wild, at least in my backyard, are in their largest numbers during the winter months and decline in the summer. Most of the monarch butterflies in the U.S. are in the temperate ranges away from the stiffling heat and humidity of the tropics or near tropics and feeding, as larva, predominately on common milkweed, A. syriaca, and other native species in the range.

Speaking of aphids, these abstracts were posted to the dplex list. It appears I am not the only one interested in chemical changes in the host plants.

Density-dependent reduction and induction of milkweed

cardenolides by a sucking insect herbivore

Martel JW, Malcolm SB


30 (3): 545-561 MAR 2004


Document type: Article Language: English Cited

References: 32 Times Cited: 0 Explanation


The effect of aphid population size on host-plant

chemical defense expression and the effect of plant

defense on aphid population dynamics were investigated

in a milkweed-specialist herbivore system. Density

effects of the aposematic oleander aphid, Aphis nerii,

on cardenolide expression were measured in two

milkweed species, Asclepias curassavica and A.

incarnata. These plants vary in constitutive chemical

investment with high mean cardenolide concentration in

A. curassavica and low to zero in A. incarnata. The

second objective was to determine whether cardenolide

expression in these two host plants impacts mean A.

nerii colony biomass (mg) and density. Cardenolide

concentration (mug/g) of A. curassavica in both

aphid-treated leaves and opposite, herbivore-free

leaves decreased initially in comparison with

aphid-free controls, and then increased significantly

with A. nerii density. Thus, A. curassavica responds

to aphid herbivory initially with density-dependent

phytochemical reduction, followed by induction of

cardenolides to concentrations above aphid-free

controls. In addition, mean cardenolide concentration

of aphid-treated leaves was significantly higher than

that of opposite, herbivore-free leaves. Therefore, A.

curassavica induction is strongest in

herbivore-damaged tissue. Conversely, A. incarnata

exhibited no such chemical response to aphid

herbivory. Furthermore, neither host plant responded

chemically to herbivore feeding duration time ( days)

or to the interaction between herbivore initial

density and feeding duration time. There were also no

significant differences in mean colony biomass or

population density of A. nerii reared on high

cardenolide ( A. curassavica) and low cardenolide ( A.

incarnata) hosts.


Author Keywords:

Aphis nerii, Asclepias, cardenolide, chemical defense,

herbivory, induction, milkweed, reduction,

sequestration, specialist, trophic interactions


KeyWords Plus:





Malcolm SB, Western Michigan Univ, Dept Biol Sci,

Kalamazoo, MI 49008 USA

Western Michigan Univ, Dept Biol Sci, Kalamazoo, MI

49008 USA




NY 10013 USA


IDS Number:






Well, A. curassavica does change. The strange thing is if I feed monarch larva in the summer on undamaged plants, they still die, and in the winter, if I feed them on aphid infested plants, and I have feed them that way (one of my "mad scientist" moments), they survive.


Specificity of induced plant responses to specialist

herbivores of the common milkweed Asclepias syriaca

Van Zandt PA, Agrawal AA


104 (2): 401-409 FEB 2004


Document type: Article Language: English Cited

References: 70 Times Cited: 0 Explanation


Induced plant responses to herbivory appear to be

universal, yet the degree to which they are specific

to sets of herbivores is poorly understood. The

generalist/specialist hypothesis predicts that

generalist herbivores are more often negatively

affected by host plant defenses, wheras specialists

may be either unaffected by or attracted to these same

"plant defenses". Therefore, specialists should be

less predictable than generalists in their responses

to induced plant resistance traits. To better

understand the variation in plant responses to

herbivore attack, and the impacts these responses have

on specialist herbivores, we conducted a series of

experiments examining pairwise interactinos between

two specialaist herbivores of the common milkweed

(Asclepias syriaca). We damaged plants mechnically,

with swamp milkweed beetles (Labidomera clivicollis),

or with monarchs (Danaus plexippus), and then asessed

specificity of elicitation, both by measuring a

putative defensive trait (latex volume) and by

challenging plants with insects of both species in

bioasays. Latex production increased by 34%, and 13%

following beetle and monarch herbivory, respectively,

but only beetles significantly elevated latex

production compared to undamaged controls. While

beetle growth was negatively affected by latex across

all experiments, beetles were not affected by previous

damage caused by conspecifies or by monarchs. In

contrast, monarchs feeding on previously damaged

plants were 20% smaller, and their response was the

same on plants damaged mechnically or by either

herbivore. Therefore, these specialist herbivores

exhibit both specificity of elicitation in plant

responses and specificity of effects in response to

prior damage.


KeyWords Plus:







Van Zandt PA, Washington Univ, Dept Biol, Campus Box

1137,1 Brookings, St Louis, MO 63130 USA

Univ Toronto, Dept Bot, Toronto, ON M5S 3B2, Canada






IDS Number:







Poorly understood ... no kidding. Why are the monarchs 20% smaller?

I guess I should go take a look at the entire paper.

August 16, 2004.

This morning, an adult monarch emerged from its pupa in perfect condition. I found two caterpillars recently. One formed a smaller pupa and died. The second is the butterfly we have today. It seems, in July, there is a small window of opportunity for monarch survival. I have no real clue as to why, but I seem to find a few outside every year during this time period, and then none again until the late fall. The larva I have grown in controlled conditions also perk up and survive much better, but then, in August, they go back downhill, and they have again. I am of the opinion this is tied to the changing chemistry within the plants, A. curassavica, but how to measure this precisely is beyond my current capabilities with the exception of observation of changing circumstances over time.

December 17, 2004

It is hard to believe so much time has passed without making an entry, but I have had many distractions this past year.

First, after many years of looking, a tagged butterfly finally made it into my backyard. The tag info from my postings on dplex are below:


On Tuesday, December 7, 2004, at 08:15 PM, Dale McClung wrote:

After years of observing, I finally found that a tagged Monarch butterfly had reached my backyard. The butterfly arrived the first week of November. I netted a few gravid females to restart my breeding stock at that time. The fall migrants are generally very healthy butterflies and I abandon my summer stock for fresh genetics. I found the butterfly expired as I was cleaning the aviary later. To my amazement, there was this tag.

The tag is not a MW product. It is folded over the wing rib and square.

It reads:

Mail to


Box BF

24595 VA



Is anyone familiar with this program? I would like to send the tag in, but I am unsure the address as written on the tag is sufficient for mail delivery. If it is OK, I will send the tag in.

Dale McClung


This is a Monarch Monitoring Project tag from Cape May, NJ. See:


I'll send you details on exactly when and where it was tagged.

Do you have an arrival date and a specific location?

Thanks, Dick Walton, Director MMP


Monarch #145585 was tagged on the morning of October 19 at 418 Cambridge, Cape May Point, NJ by (name not mentioned here for individual privacy). Its wing measurements were 54/31, it was very fat, and its overall condition was below average. Can you give us exact dates on capture and your locations.


My zip code is 33710 in St. Petersburg, FL. Early November, probably 7-9, is when the monarch, gravid female, arrived. I netted a few females, 2 or 3, to collect some fall migrant eggs. I found the tag Nov. 18 while clearing the aviary of expired butterflies. The butterfly is in poor condition now. However, I have the specimen. Where would be best to mail it?


Thanks for the info. Mail to:

Lincoln Brower

2850 Cub Creek Rd.

Roseland, VA 22967


For those unfamiliar with Dr. Lincoln Brower, he is a renown expert on the monarch butterfly. For a profile, go to


I had the pleasure of meeting Dr. Brower a few years ago on a field trip sponsored by the Audubon Society. They host an annual butterfly and bird festival event here. He was one of the featured speakers and hosted a field trip I participated in.


The tagged butterfly made the trip from Cape May, NJ, to my backyard in about three weeks. The route is known as "the East Coast flyway."

As for the other observations since my last entry, monarchs have been relatively few, and I have yet to see any males this fall, only females laying eggs, one or two at a time only. The "malady" is running its usual course. The butterflies I am raising now are improved in health, but there are still casualties, just much more reduced in number.

We will post further observations as warranted.

Dale McClung

St. Petersburg, FL

Thanks for visiting.

Dale & Peggy McClung