5-8 Elementary/Middle School
This change-over-time, construction of an explanation activity serves 2 purposes. First, students observe development of 3 different insects from the larva or nymph stage through the adult stage. Second, students complete a comparative development study of metamorphosis, observing complete and incomplete metamorphosis. Students hone their observation skills while their drawings serve as traditional, biological qualitative data. Student drawings are used to explain the life cycles of the 3 insects. If well cared for, the insects may be kept in habitats for their life span and used for additional activities.
What are the life cycles of insects?
Constructing Explanations
LS1.4.A
Structure and Function
Safety goggles and safety gloves are required.
Provide a habitat and follow all care instructions for each of the 3 species throughout the observation period.
Each student or group will need one individual from each species. Each organism needs its own container as the lady beetle larvae will eat the other 2 species.
Treat all animals with care and respect. Non-native species should not be released into the wild. Any individual insects remaining may be kept in a permanent habitat or placed in a resealable bag and put in the freezer for 72 hours, and then disposed of as your state or district directs.
See pictures of life cycles below for what each stage should look like. You may want to take pictures of each stage in the life cycle for documentation and as an assessment tool later.
1. Use the drawings in your observation sheets to make life cycle diagrams for all 3 insects. Label the life cycle stages. Include the number of days in each life cycle stage.
Student answers may vary in time frame but should be similar to the cycles below.
Approximate times for each stage:
| Painted Lady Butterfly | Lady Beetle | Milkweed Bug | |
|---|---|---|---|
| Egg | 3-5 days | 4-6 days | 4-7 days |
| Larva | 5-10 days | 10-14 days | n/a |
| Pupa | 7-10 days | 3-12 days | n/a |
| Nymph | n/a | n/a | 5 instars, 20-40 days |
2. Label each of the 3 cycles as complete metamorphosis or incomplete metamorphosis. Explain your thinking.
See picture above for the labeling. Student thinking should be based on the number of distinct stages that the insect goes through.
3. Draw a Venn diagram for the stages of metamorphosis. Label one circle Complete and the other circle Incomplete. Label the shared area Both. Fill in the sections of the Venn diagram. Include the name of an insect for each type of life cycle.
4. Optional assignment: What are 2 advantages and disadvantages of each type of metamorphosis?
Answers may vary.
Complete metamorphosis
Advantages: Typically, adults and larvae do not compete for the same food source, do not have the same predators, and occupy different habitats.
Disadvantages: Adults and larvae do not share the same food, which can be a disadvantage in food-poor environments; short adult life span; only adult has true mobility.
Incomplete metamorphosis
Advantages: No vulnerable pupa stage; parental protection can occur; mobility throughout life cycle.
Disadvantages: Nymphs compete with adults for food and habitat; share the same predators.
Oncopeltus fasciatus. This attractively colored bug has been used extensively in research ranging from biochemistry to behavior.
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