University of Minnesota

Ecology Fair University of Minnesota Monarch Lab

Abstracts from Willow Creek Middle School 1998

Willow Creek Middle School
2425 11th Ave SE
Rochester, MN 55604

Year: 1998
Teacher(s): De Cansler

Do Monarch Larvae Prefer Young Or Mature Milkweed Leaves?

Beth Z

I gave 7 monarch larvae a choice of ingesting newly sprouted common milkweed leaves or mature leaves in a controlled environment and recorded their daily consumption.  The purpose of this experiment was to determine whether or not monarch larvae would display a diet preference. In the end, 48% of the larvae tested consumed new leaves, 14% consumed mature leaves, 19% did not show a preference, and 19% were not active due to molting.  Only 7 larvae (A-G) were tested (although their milkweed consumption was observed daily for a total of 36 experimental repetitions).   Individual larvae results were as follows: 4 preferred new leaves, 1 preferred mature leaves, and 2 did not show any observable preference. I believe testing a greater number of larvae and observing their preference for only one day per larvae would increase the accuracy of my results.  My data does seem to indicate that monarch larvae do prefer the newly sprouted milkweed leaves over the more mature ones.  It is interesting to note that individual larva were sometimes observed on both sides of the experimental container but only ate the new leaves.

Does Heat Or Light Effect The Direction Of The Pre-Pupal J?

Brad L, Sopaula N

We used 8 copy paper boxes with 8 plastic tubs inside them.  Four boxes had 4-inch square holes cut in one end and the other 4 boxes had no openings.  We put the boxes 10 inches away from a 40-watt light bulb in a north, south, east, and west orientation.   We put seven 5th instar monarch larvae in each of the tubs and then put the tubs into the boxes.  In the boxes with openings exposed to the light, the larvae always "J"ed away from the light, regardless of the direction of the opening.  The larvae in the closed boxes "J"ed in many different directions.  We are uncertain if there are other factors that determine the direction of the "J".   We learned that monarchs pupate with their backs to the light.  It is probably less sleeping with the lights off instead of having them shine in your face!

Does The Size Of The Container Effect The Larva Size Or Adult Size?

Megan H, Jenny R

We wanted to find out if the size of the container affected the size of monarch larvae or adults.  We found four "critter cages" that were exactly identical except for size: small, medium, large, and extra large.  We put 10 first instar larvae in each cage and kept all other variables constant.  We weighed them every day.  When they became adults, we weighed them and measured their wingspan.  The smallest container produced the heaviest larvae and the largest container produced the lightest larvae.  Also, the ones in the smallest container pupated faster and came out of their chrysalides sooner.

If There Is NO MILKWEED, Where Will Monarch Butterflies Lay Their Eggs?

Elissa C, Giulia R

We put 10 female butterflies in a tent with no milkweed.  Instead, we gave them an assortment of egg-laying surfaces: light green paper, dark green paper, and green plastic.   All of these were cut in the shape of milkweed leaves.  Some of each kind were rubbed with milkweed latex, others were plain.  We attached the fake leaves to a branch with clothespins.  The purpose was to find out what they would lay their eggs on if there wasn't real milkweed.  They didn't pick any of the fake leaves.   They laid their eggs on the sides of the tent and on feeding sponges instead!   We learned that it was not so easy to fool the butterflies, and that they will lay their eggs, but not on fake leaves.

The Affects Of Different Species Of Milkweed On Monarch Development

Janelle F, Julia G

We wanted to find out how different species of milkweed affected developing monarchs.   We raised 100 monarch butterflies from eggs: 20 on swamp milkweed, 20 on common milkweed, 20 on whorled milkweed, 20 on tropical milkweed, and 20 on butterfly weed.   All conditions other than food were controlled (held constant).  Larvae fed on tropical milkweed had the highest survival rate and the shortest time to pupation.   Larvae fed whorled milkweed and butterfly weed had the lowest survival rate and the longest time to reach pupation.  Common and swamp milkweed were in the middle.   We are uncertain about the causes of the high mortality in our experiment.  We learned that diet is an important factor in larval development.  We also learned that doing an experiment like this is a lot of fun...but also work!

The Affects Of Magnets On Monarch Development

Chris R

I watched the caterpillars and checked which direction they would "J".   On the side of the containers I placed a powerful magnet.  I did this to determine if the direction of the "J" was affected by magnetism.  However, the direction of the "J" appears to be largely random.  Only 19 caterpillars were tested, however; so if a larger number were checked, a definite pattern might emerge.  My science teacher, Mrs. Cansler, performed a similar experiment with similar results.  However, while I had a magnet attached to one side, her experiment consisted of two magnets, one above and one underneath the cage. Two things I learned during the testing were that the bad taste of a monarch does not deter spiders (one got into one of the cages, which is why I only had 19 monarchs "J").  Also, that the size of a monarch is not always an indication of its age, as I had several smaller caterpillars "J" while the larger ones continued eating.

  • © 2015 Regents of the University of Minnesota. All rights reserved.
  • The University of Minnesota is an equal opportunity educator and employer. Privacy