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Ecology Fair University of Minnesota Monarch Lab

Abstracts from St. Hubert School 2002

St. Hubert School
8201 Main St
Chanhassen, MN 55317

Year: 2002
Teacher(s): Cindy Petersen

Choices, Choices, Choices

Nick S

In my first experiment, I visited Spring Peeper Meadow once a week for three weeks and looked at a total of 50 sprayed and 50 healthy milkweed plants.  I recorded their height, condition, numbers of monarch eggs and larvae and number of other invertebrates on each plant.  The sprayed milkweed plants received drifted spray from Round-up herbicide that was used to kill reed canary grass.  For the second part of the experiment I got 15 pregnant female monarchs and gave them three different types of milkweed to lay eggs on; healthy, drifted sprayed plants and directly sprayed plants.  I recorded how many eggs they laid on each type of plant then took 15 eggs from each treatment and raised the larvae on each type of plant.  I recorded information as they grew, and when they became adults, I measured their wingspan and weighed them.  My purpose was to see how Round-up sprayed on milkweed affected monarch growth and development and if pregnant females make a choice on what plants to lay eggs on. At Spring Peeper there was an egg or larvae every five sprayed plants, but there was an egg or larvae found on every three healthy plants.  In the controlled experiment, 14% of the eggs on directly sprayed plants survived, 20% of the eggs survived on drifted sprayed plants and 60% of the eggs on healthy plants survived.  From 213 eggs total, 115 were laid on healthy plants, 79 on drifted sprayed plants and 19 on directly sprayed plants. Some uncertainties were I checked different plants every week in the field and I could not check them the same time every week.  Some new things I learned were females prefer healthy milkweed, then drifted sprayed then directly sprayed milkweed to lay eggs and grow on.


Egg-Sighting!

Jessica P, Kelly O

In this experiment we placed 15 pregnant monarch butterflies in a cage with six swamp milkweed treatments and six common milkweed treatments.  We also placed half of the milkweed in the shade and half in the light.  We recorded how many eggs were laid on what type of milkweed, whether eggs were laid in the sun or shade, the time of day and whether it was on a green or yellow leaf.  We wanted to find out how different factors; type of milkweed, shade vs. light, green vs. yellow leaves and time of day affect monarch oviposition. We found that monarchs prefer to lay eggs on the top of the milkweed in the field but bottom in a tent.  They prefer swamp milkweed, sunlight, green leaves and lay eggs from noon to 8:00 PM. During our experiment a few things happened that may have affected our results.  One example is that a few of our butterflies died.  This changed the number we had each day to work with.  This experiment taught us a lot about monarchs and where they lay their eggs.


Feeding Frenzy

Alyson B

For my experiment, I fed monarch larvae the top, middle and bottom sections of the milkweed plant (Asclepias syriaca).  There were a total of 60 monarch first instar larvae with ten larvae in each cage.  Two cages had milkweed from the top of the milkweed plant, two cages had milkweed from the middle of the plant and two had milkweed from the bottom.  The larvae went through metamorphosis after eating their section of milkweed each day.  When they became adult monarch butterflies, I measured their weight and length of their wingspan.  I wanted to know how feeding monarch larvae the top, middle, and bottom section of the milkweed plant affects the overall growth of the butterfly.  I also wanted to find out where monarchs were most likely to lay eggs on a milkweed plant in nature; top, middle or bottom of the plant. I found that the monarchs that fed off the top of the plant tended to weigh more than those butterflies that fed off the middle or bottom of the plant.  I also found that the monarchs that ate off the top and middle of the plant grew to have larger wingspans than the larvae that fed off the bottom of the plant.  What I found from doing field research was that the most common place for monarch butterflies to lay their eggs was on the top section of milkweed. I am uncertain if the exact measurements of the butterflies wings are accurate because I was measuring using a millimeter ruler.  My numbers could have been off slightly.  One new thing that I learned was that monarch larvae that were fed the top section of the milkweed plant grew to weigh more than the larvae that fed off the middle or bottom of the milkweed plant.  I also learned that it takes three to four weeks for a monarch to go through complete metamorphosis.


It's an Insect Eat Insect World: Ant-Aphid Relationships

Colin H

For my first experiment, I placed 40 monarch caterpillars, one at a time and at different distances, on a milkweed plant with an ant/aphid colony to see how much time it took for the ants to attack the larvae.  In the second experiment I got five ant/aphid milkweed plants and five healthy plants and put them in a cage with five pregnant monarch butterflies to see if they would lay their eggs on aphid plants as well as healthy one.  For the third question, I went to a restored meadow and measured the size and characteristics of 30 ant/aphid colonies and also measured the abundance of ants and aphids on milkweed. For question one, I wanted to find out how the stage of larvae and the distance placed from the aphid colony affects the time and frequency of ant attacks.  In question two, I was trying to find out how having ants and aphids on a plant affects monarch oviposition.  For question three, I wanted to find out what the abundance and size of aphid colonies are in a restored meadow. I found that the ants attack more quickly and often when the larvae are close to the colony and pose a threat to the ants and aphids.  In question two, I found out that the monarchs dont seem to care it there are ants/aphids on the milkweed to lay their eggs.  In fact, they laid more on the milkweed with the ants and aphids than the plants without.  For question three, I found that the size of the colony ranged from 2-11 cm with 1-6 ants tending the aphids.  The abundance of ants and aphids on milkweed plants in the meadow that also had monarch eggs and larvae was 5%. On thing I dont understand is how aphids make a sweet juice from eating latex textured milkweed.  I learned that ants are able to milk the aphids, or coax the aphids into making more honeydew.  I also learned that the ants are very protective of the aphids just because they get something out of it.  Its just an insect eat insect world out there!


Monarch Oviposition and Growth

Brigid O

I randomly placed two stems of common milkweed (Asclepias syriaca), two stems of swamp milkweed (A. incarnata), and two stems of tropical milkweed (A. curassavica) in a 6 ft. x 6 ft. x 6 ft. mesh tent and observed which species monarch butterflies preferred to lay eggs on.  For my second question I gathered 40 eggs, 20 from common milkweed and 20 from swamp milkweed.  I raised the caterpillars through metamorphosis feeding them either common or swamp milkweed, observed the growth of monarchs and measured the size of the adults.  I wanted to find out which species of milkweed (common, tropical or swamp) produces the biggest monarch. For my first experiment I found out that pregnant females prefer to lay eggs on common milkweed.  For my second experiment I discovered that swamp milkweed produced the biggest adults.  I was uncertain about my egg laying numbers because they might have laid more eggs, but it started to rain at 4:00 in the afternoon and they stopped laying.  I learned that swamp milkweed produces the biggest monarchs and females prefer common milkweed to swamp and tropical for oviposition.


Prowling Predators

Jorie G

I collected monarch eggs and larvae and put them into six different cages. Then I gathered 30 ants and six spiders on milkweed plants in a field. I split the 30 ants into three of the cages having ten ants in each cage. I did the same with the spiders having two spiders in each cage. I recorded how many eggs and larvae were eaten at the end of each day for four days. I also did a field study between June and September and surveyed the number of ants and spiders present on milkweed plants that also contained monarch eggs and larvae. I wanted to find out how ants and spiders affect the predation on monarch eggs and larvae, and how the presence of spiders and ants affect monarch adult egg laying choices in the field. I found out that ants are the major predator of the two. Ants ate 21/71 eggs and 1/22 larvae. Spiders only ate 5/20 eggs and no larvae. A major uncertainty throughout this experiment was that almost all of the eggs used at the beginning of the experiment hatched before the end of the experiment so the number of eggs and larvae in each cage changed daily. I learned that ants and spiders do affect predation of monarch eggs and larvae, and that ants are the main predator out of the two both in a controlled setting and in the field.


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