One axis that is helpful in the life-cycle arena is comparing organisms that exhibit different types of development.  That may include:

• Complete and incomplete metamorphosis in insects
• Metamorphosis in amphibians
• Alternation of generations in plants

This article discusses investigations of invertebrates that undergo complete metamorphosis.

Step 1) Find insects.  In Fairbanks Alaska during the winter, this can be a bit difficult.  However, it is fortunate that we have a largish pet store here in town.  A great organism for hands-on insect investigation is the Darkling beetle (Zophobas morio) larva, otherwise known as the superworm.  Note that the term “worm” is a misnomer, because they are in fact insect larva with 3 pairs of fully-arthropodic legs. Second, the “super” part is a takeoff from the more common meal worms.  Meal worms are also beetle larva.  For hands-on insect explorations, however, I highly recommend the superworms over the meal worms for several reasons:

1) superworms are much larger
2) superworms are far more active
3) superworms are really tough, and hold up well to handling (and the occasional drop)

The one downside with these organisms is that the adults are reported to put off a fairly offensive odor.  So, if you purchase a tub of darkling beetle larva, you’ll want to have thought through an exit strategy to employ after you have finished experimenting with these organisms.  Fortunately for me, I know several families who raise chickens and ducks, who are glad to take these tasty snacks home for their pets.

Step 2) Experiment.  Here are a few investigations kids can do with superowrms, as usual, the list of the ideas goes in increasing difficulty, but as usual older kids are not discouraged from doing any of the projects.  It continues to be my experience that many kids like to revisit certain activities they’ve done before, and I am sure they learn something new in the process.

• Count legs (if child hasn’t seen one before, begin the investigation by not telling them what the organism is), then let them guess.
• Measure length
• Measure burrowing rate – how fast will a darkling beetle dig into the food medium
• Observe burrowing behavior (notice that often darkling beetle larva travel in reverse!)
• Observe larva’s behavior when placed on a table top
• Observe the larva’s behavior when placed in a small pile of food medium on a table top (generally, they will venture out, in a few directions, recognize where the boundary is, then burrown into the pile and stay there)
• Build a track and place potential food items along the path observe the insect’s behavior
• Build a track and place piles of potential burrowing stuff
• Build a maze and place potential food items at regular intervals
• Build a maze and place piles of potential habitat (wood shavings, grains, etc)

Math ideas

• Count legs
• Measure lengths of larva
• Calculate the animal’s rate of travel.
• Measure how far the insect travels in a given time (say 10 seconds)
• Measure how long it takes for the insect to travel a given distance (say 100 cm)
• Calculate average length of 3 or more larva
• Calculate average rate of travel of 3 or more larva

Take it further.

1) Look up the following vocabulary words:

• Egg
• Larva
• Pupa
• Adult
• Metamorphosis

2) Study darkling beetle life cycles.  How long, on average do they spend as larva, pupa and adults.

3) Find photographs of adult darkling beetles online.

Please let me know how you enjoy working with these interesting organisms.