Grasshopper Breeding Basics: First, Know the Species
The two representative grasshoppers commonly seen in Japan are the Japanese locust (Locusta migratoria) and the slant-faced grasshopper (Acrida cinerea). Both are active as adults during summer through autumn (July–November) and are familiar classics in children's insect collecting.
| Characteristic | Japanese Locust | Slant-faced Grasshopper |
|---|
| Body Length (♀) | 40–55 mm | 70–80 mm (Japan's largest grasshopper) |
| Body Color | Brown to green (individual variation) | Green (♀) · Brown (♂) |
| Hind Wings | Tinged with blue | Pale yellow-green |
| Habitat | Grasslands, farmland | Tall grassland, embankments |
| Flight Ability | Strong, long-distance | Moderate |
| Calling Sound | Rarely makes sound | ♂ chirps (while flying) |
Phase Polymorphism (Japanese Locust): As population density increases, the Japanese locust transitions from solitary to gregarious phase, with dramatic changes in body color, wing shape, and behavior (increased flight ability and darker coloration). In breeding environments, keeping 1–2 individuals is standard practice; inducing the gregarious phase is avoided.
Grasshopper Breeding Quick Reference
| Item | Japanese Locust | Slant-faced Grasshopper |
|---|
| Adult Lifespan | 2–3 months | 2–3 months |
| Primary Diet | Poaceae (foxtail grass, etc.) | Poaceae (foxtail grass, etc.) |
| Egg-laying Site | Underground (10 cm+ deep) | Underground (foam-enclosed egg case) |
| Overwintering | As eggs (adults do not overwinter) | As eggs |
| Nymph Diet | Soft grass shoots (Poaceae) | Soft grass shoots (Poaceae) |
Lifespan, diet, egg-laying, and overwintering are largely common between the two species.
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Collection Tips and How to Transport Home
Collection Season: Peak season is early July through late October, with particularly high numbers of adults in August–September.
Collection Sites:
- Japanese Locust: Riverbanks, grasslands and vacant lots near farmland
- Slant-faced Grasshopper: Embankments and fields with tall grasses (Miscanthus, cogon grass)
Collection Equipment:
- Insect net (large mesh is ideal)
- Breeding container (use a breathable container after collection)
- Cooler bag (for temperature control during transport)
Transport Notes: Grasshoppers are sensitive to heat, so avoid direct sunlight and leaving them in vehicles. Move collected specimens promptly to a breeding container in a cool place. Since grasshoppers are highly active jumpers, prioritize breathability over airtightness in the container.
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Setting Up the Breeding Container
Since grasshoppers excel at flying and jumping, a vertically spacious container is ideal.
Recommended Container: A plastic container (large) at least 30 cm tall for insect breeding, or a mesh cage (fabric, highly breathable) at least 100 cm tall. Particularly large female slant-faced grasshoppers can be easily injured in cramped environments.
Bedding:
- Spread soil or coconut husk soil 3–5 cm deep for a more natural environment
- No bedding (prioritizing cleanliness) is also acceptable, but add wooden branches or artificial plants as perches
Perches and Footholds:
- Place several thin wooden branches
- Live grass plants (foxtail grass, cogon grass) in pots serve as both food and perches
Temperature and Humidity:
- Temperature: 25–32°C (sensitive to cold)
- Humidity: 50–70% (slightly dry is acceptable)
- Place in a bright location while avoiding direct sunlight
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Feeding
Grasshoppers are herbivorous and feed primarily on grasses. Providing fresh food daily is essential for their health.
Primary Foods:
- Foxtail grass: The most commonly eaten staple
- Cogon grass, Miscanthus, Japanese lovegrass, crabgrass: Wild grasses
- Wheat sprouts, rice sprouts: Home-grown edible plants can also be used
- Cabbage and lettuce leaves: Can be used as supplements (beware of excess moisture)
Tips for Feeding:
1. Collect wild grasses from pesticide-free areas
2. Rinse to remove excess soil
3. Replace with fresh grass every other day (they won't eat stale vegetation)
4. Place directly on the container floor or insert into a small vase with water to extend freshness
Hydration: Since grasshoppers obtain sufficient water from plants, a separate water dish is unnecessary. However, light misting of leaves during hot weather can be helpful.
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Molting and Growth Management
Grasshoppers undergo 5–6 molts to reach adulthood (nymph stage: 5–7 instars). Immediately after molting, their bodies are soft and they may be eaten by other grasshoppers in the container, so caution is necessary.
Pre-molting Signs:
- Decreased appetite
- Become quiet and cling to footholds
- Body color slightly darkens
During Molting:
- Never touch during the process
- Ensure footholds (branches, stems) are secure
- Leave undisturbed for 6–12 hours after molting until the body hardens
Post-molting Appetite Recovery: Appetite returns the day after molting. Provide plenty of fresh grass.
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Egg-laying and Egg Management
Adult grasshoppers mate and lay eggs. Since they lay eggs underground, prepare soil (mixture of red ball clay and leaf mold) at least 10 cm deep in the breeding container.
Egg Count: Each egg-laying produces 20–100 egg cases. Slant-faced grasshoppers notably produce egg cases with substantial foam.
Overwintering: Japanese grasshoppers do not survive winter as adults. Adults die as fall ends, and eggs in the soil overwinter, hatching in spring.
Egg Management:
- Keep soil with eggs in a container in a shaded outdoor location for winter
- Wait for nymphs to hatch in spring (April–May)
- Mist regularly to prevent excessive drying
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Adult Lifespan and Breeding Precautions
Adult Japanese locusts and slant-faced grasshoppers have a lifespan of approximately 2–3 months. Individuals that become adults in August naturally reach the end of their lifespan around October–November.
Breeding Precautions:
- When keeping multiple grasshoppers, monitor closely for cannibalism (of molting and weakened individuals)
- Clean the container weekly and remove feces and old vegetation
- Avoid collecting from invasive species or pesticide-contaminated areas
- If releasing into the wild after breeding, limit to the original collection site
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Summary: Enjoying Grasshopper Breeding
Grasshoppers are excellent subjects for nature observation, allowing you to enjoy a full year cycle from collection through breeding and hatching. For children especially, they offer a rare opportunity to witness the life cycle firsthand—from wild collection through breeding, egg-laying, and hatching.
While it requires effort—such as gathering grass for food or preparing soil for egg-laying sites—the work itself fosters attachment and care. Grasshopper breeding is ideal for summer vacation research projects, and combining it with observation notes creates deep learning experiences.
