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Contents:
1) Welcome!
2) Status of the Population and a Prediction
7) Summer Savings at Gulliver's Gift Shop
9) Our Newest Program Assistant
10) How to Unsubscribe from this Update
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1) Welcome to Monarch Watch's Update List!
You are receiving this email because you have provided Monarch Watch with your email address at some point and expressed interest in receiving updates from us. If you do not wish to receive these periodic (probably monthly) email updates or feel that you were subscribed in error, please see the unsubscribe information at the end of this message.
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Monarch Watch (http://www.MonarchWatch.org) is a not-for-profit educational outreach program based at the University of Kansas. We run a Monarch tagging program and offer Monarch Rearing Kits, Monarch Tagging Kits, and other educational/promotional materials that allow you to actively experience the monarch life cycle and its spectacular fall migration.If you have any questions, please feel free to contact us anytime!
Your friends at Monarch Watch
http://www.MonarchWatch.org
monarch@ku.edu
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2) Status of the Population and a Prediction
by Chip Taylor
Monarchs have been reported from most of the breeding areas in the northern states and Canadian provinces. Many reports indicate that the monarchs arrived 1-3 weeks later than last year. The numbers of early monarchs are low but this is usually the case for many portions of the northern breeding range early in the season. The first generation of offspring started to emerge last week in the vicinity of the Twin Cities (45 degrees N) so there should be a few new monarchs seen by those engaged in 4th of July butterfly counts.
This first generation will be spread out into early, perhaps mid, July with a peak egglaying period in mid July. This is a bit later than usual and how this might influence the number of monarchs in the fall migration is not yet clear. Generally, in much of the northern breeding area, it is the eggs laid during the last 10 days of July and the first 10 days of August that become the adults that migrate in late August and September. Rainfall has been abundant, too abundant in some areas, across the breeding habitats and temperatures have been normal. Milkweed is plentiful and in good condition. In our location in Kansas monarchs are still scarce but we are starting to see a few. The number of eggs and larvae found on milkweeds continues to be low.
Prediction
I usually don’t attempt to give a qualified prediction concerning the fall population until I write the Premigration Newsletter later in July. At that time there are more reports of reproducing monarchs and it is easier to get a "sense" from the reports as to the size of the upcoming fall population. Here is my current assessment: the fall migration could still be quite good but it seems likely that the number of butterflies will be significantly lower than last year. The average for the overwintering population for all known colonies for the last 9 years is 9.6 hectares. (I will explain the basis for this figure in the Season Summary.)
Last year the number of hectares measured by Eligio Garcia was 9.35, a spectacular recovery from the population of 2.83 hectares measured the previous winter. Earlier I estimated that 2.5 – 3.5 hectares of butterflies survived the severe January storm. This is a low number. Nevertheless, the number of arrivals reported in Texas in March and early April (largely through the efforts of Mike Quinn, the Texas Monarch Watch, and the Texas Department of Parks and Wildlife) signaled a potential recovery of the type seen in 2001. However, in the April update I suggested that the conditions were not as favorable for a recovery this year because of an increase in the number and size of the fireant colonies in many areas and the lower winter and spring rainfall. Indeed, the lower number of reports to Dplex and Journey North of monarchs returning to the northern states and provinces in May and June relative to last year suggests that the recovery will be delayed and that it may take the the overwintering population more than one year to return to normal levels. If this is the case, it would mirror the statement to this effect that I made in the report on the winter kill posted to the web site in late January. Let’s hope that these predictions are incorrect and that the monarchs rebound, producing a large migratory population in August.
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by Chip Taylor
For the last 5 years or so I have been referring to a premigration migration, a migration of apparently reproductive monarchs that moves south beginning in late July and continuing, in Kansas at least, until mid August. I have posted a number of observations of monarchs seen moving south during this period to Dplex-L. A few others have posted similar observations and we sometimes get calls from people wondering why the monarchs are migrating so early. Monarchs generally disappear or only maintain low population densities in most areas south of 37 degrees North from mid May to August. However, the region south of 37 degrees is frequently repopulated with monarchs in August and September (before the true migration) arrives in a pattern consistent with the idea that recolonization occurs via butterflies from the north rather than from a resurgence of the local population. If this is the case, how can we explain the behavior of monarchs moving south before the true migration which generally occurs a month later? Why do these monarchs leave and what environmental cues are they sensitive to that trigger this migratory behavior? And, if some leave the north at this time, why don’t they all do it?
Given the way we think natural selection acts in these cases, it is standard to ask why it might be selectively advantageous for some monarchs to move south ahead of the true migration. One possibility is that there is a portion of the population that emerges in late July and early August too late to successfully reproduce at their respective latitudes. For example, let’s suppose that a monarch emerges in Minneapolis on the 1st of August. This butterfly requires 45 degree days (see last month’s update for an explanation of degree days) before it is sexually mature. This could mean that it would take 4-5 days before this butterfly would mate. If this monarch were a female and she started laying eggs on the 6th of August, continuing to lay eggs for the next three weeks, her first offspring would mature in 30-35 days (6-11 Sept) about halfway through the fall migration at this latitude. The mid and late offspring from this female would emerge at the end of the migration or later and would be subject to killing frosts that can start in mid to late September in Minneapolis. An alternative for this butterfly is to head south shortly after emergence. This might be more advantageous than producing offspring that might be too late for the migration. However, moving south in late July and early August does not guarantee success. It is often hot and dry during this period and the milkweeds are usually in poor condition having flowered and beginning to senesce (grow old). On the other hand, late summer rains south of 37 degrees N can rejuvenate milkweeds such as A. viridis, A. asperula, and A. oenotheroides, providing sources of food for monarch larvae. Thus, although a southward migration prior to the real migration might not be successful, the probability of success could be high enough to be favored by selection. If so, this still leaves the question as to the environmental information that the butterflies might use as a cue to initiate the migration. At this time we don’t know what information the butterflies use but the celestial information, in terms of sun angle, during this period is similar to that during the period when the first generation monarchs are moving north in May.
If the scenario I’ve outlined above is true, the size of the premigration migration is likely to be a function of the number of butterflies emerging in this critical period and this in turn is related to the time of arrival of monarchs in the early summer and the overall size of the population. It also follows that the reproductive success of the butterflies moving south is dependent on the condition of the milkweeds and the availability of nectar sources to sustain the adults and both of these are dependent on soil moisture and rainfall. It could be that there are years when the premigration migrants produce enough progeny to contribute significantly to the overwintering population.
Is there a premigration migration? You can help by reporting to monarch@ku.edu or to Dplex-L (http://www.MonarchWatch.org/dplex) what you see monarchs doing in your area during the period from the 15th of July to 15 August.
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When we think of silk it is usually in connection with clothing produced from the silk harvested from the cocoons of silk moths or the webbing used by spiders to catch prey. However, the larvae of most Lepidoptera produce silk as well. Many of you are familiar with the silk mat that monarchs lay down before pupation. During the last molt, at the time of pupa or chrysalis formation, the cremaster which forms beneath the cuticle of the larval anal prolegs, is thrust into this silk mat. The crochets (hooks) on the cremaster "hook" into the mat holding the pupa in place (head down). Less well known is the fact that monarch larvae produce silk throughout their development. In fact, most of the time larvae, unless moving from place to place or feeding, spin a silk mat upon which they crawl or rest and they produce a distinct silk mat on which they position themselves at the time of each molt.
The silk is produced from a single spinneret located under the head:
http://www.MonarchWatch.org/update/2002/spinneret.html
The silk secreted from the spinneret is a liquid that hardens immediately upon contact with the air. If you want to watch how monarchs produce silk, place a larvae in a clear plastic cup. If the cup is slick, the larva will not be able to climb up the sides since the crochets on the prolegs will not be able to grip the plastic. The larva will respond by weaving its head from side to side and will lay down a mesh of silk which can be gripped by the prolegs and after a few minutes the larva will be able to progressively advance upward by grasping the silk with the crochets. Monarch larvae produce a surprising amount of silk but there are no estimates of the length or mass of the silk produced in a larva’s lifetime. The length of silk produced in a given period would not be too hard for a student to estimate by using the method suggested above.
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We will begin shipping tags during the last week of this month first by zipcode (northern taggers first) and then in the order that the orders were received. We will continue to take orders for the 2002 season tags until we run out or until October 10th; however, since we have run out of tags early the past two seasons, it is not safe to assume that we will have them available later in the season. In other words, order your tags today! ;-)
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Raise monarchs at home or in the classroom! If you live in the United States (east of the Rocky Mountains) we can send you Rearing Kits so that you can experience the amazing transformation of monarch caterpillars into pupae and then watch them emerge as adult butterflies. More information and instruction is available on our site at
http://www.MonarchWatch.org/rear
and you can order them via Gulliver's Gift Shop at
(mail, fax, and phone orders are accepted there as well).
We receive a lot of requests in the fall and larvae are provided on a first come, first serve basis. If you want to be sure to receive your rearing kits when you want them, place your order as early as possible and specify your preferred ship date.
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7) Summer Savings at Gulliver's Gift Shop
Summer is the time for T-shirts so why not show everyone that you support Monarch Watch with our beautifully silk-screened Migration T-shirt? The shirt is 100% cotton and has flying monarchs silk-screened in vivid colors on the front and back. Gulliver (the Monarch Watch "Logopillar") appears on the both front and back so everyone who wears one will be helping us spread the word about Monarch Watch. The shirt comes in sizes Adult Medium to Adult XX-Large and usually costs $17. Enter coupon # MW072002 at check out and you will save 15% ($2.55) so the shirt will cost you $14.55! There are limited quantities and this offer is only good for 2 weeks so order today. Remember, each and every sale in Gulliver's Gift Shop supports Monarch Watch. Thanks!
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It was three years ago when I was finishing my undergraduate degree here at the University of Kansas and was offered a position as a program assistant with Monarch Watch. Little did I know the extent to which this program would impact my life. From raising monarchs with students in our lab to delivering school supplies to students in Mexico, there have been many experiences I will cherish. I consider myself lucky to have had the opportunity to become involved with this unique program.
I have met many wonderful people, and would like to say thank-you to those I have worked with during the last three years. Chip, Jim, Dana, Janis and Sarah (and the "new" Sarah too ;-), you have all been great teammates from whom I have learned so much. Though the thought of leaving saddens me, I am hopeful my upcoming endeavors as a botany student at Texas A&M will be as gratifying as this one. I will truly miss you all! --Cathy
[We'll all miss you too!! Good Luck! - Jim]
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9) Our Newest Program Assistant
We would like to extend a warm welcome to our newest program assistant, Sarah Schmidt. Sarah recently graduated from Truman State University with a bachelor's degree in biology. She will be coordinating our tagging program, helping to maintain our live monarch culture, and working on several other projects to help keep our program running smoothly. We think Sarah will be a great addition to Monarch Watch and hope that she will find this to be a rewarding position. Welcome aboard!
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