Jamaican Field Crickets

🔤 Taxonomy

Gryllus assimilis is the currently accepted scientific name in GBIF for this feeder cricket.

Common names used in the feeder trade:

• Jamaican field cricket
• Silent cricket

📌 Description

Jamaican Field Crickets (Gryllus assimilis) are live feeder crickets used for insect-eating reptiles, amphibians, tarantulas, mantids, and other captive insectivores. They are active prey, easy to buy in bulk, and useful for gut-loading, but they spoil quickly when kept damp, crowded, or dirty.

Adults are small to medium-large crickets depending on line and age. They jump, hide well, chew soft materials, and adult males call. Use crickets as part of a varied feeder rotation; no cricket species is a complete diet by itself.

Trade use of the name can be loose; buy by reliable supplier identity and colony performance, not by the common name alone.

🌍 Distribution

The name is tied to Caribbean and nearby American records, while feeder trade lines may not represent a single simple locality.

In care, the exact map matters less than biosecurity: commercial feeder crickets move through trade far beyond their native ranges, so escaped animals should never be treated as harmless.

⚖️ Regulations and safety

Gryllus assimilis is not listed in the CITES Appendices in the official CITES checklist reviewed for this guide. No specific EU wildlife trade Annex listing was found for the species.

The EU Invasive Alien Species Regulation restricts species on the Union list; this guide does not treat Gryllus assimilis as a Union-list species. Local and national rules can still restrict live insect imports, transport, breeding, sale, use in schools or workplaces, and disposal.

The Bern Convention is not normally relevant because this is not a European native protected-species care issue. Keep colonies secure, never release live feeder crickets, and freeze surplus or unwanted insects before disposal where local rules allow.

🤌 Husbandry

A practical cricket colony needs warmth, airflow, dry hiding space, moisture from safe sources, and frequent cleaning. A smooth plastic tub with a secure ventilated lid is usually easier to manage than a glass aquarium.

Good setup:

• Smooth-sided plastic tub or escape-resistant insect box
• Large mesh-covered ventilation panels
• Vertical egg crates or cardboard drink trays
• Dry floor with removable food dishes
• Separate moist food or water-gel area
• Secondary sorting tub for feeding and cleaning

Keep crickets away from pesticides, aerosols, cleaning fumes, and wild-caught insects. Do not mix old shop tubs into a breeding colony without quarantine.

💡 Lighting

Feeder crickets do not need UVB. A normal room day-night rhythm is enough. Keep colonies out of direct sun because plastic tubs overheat rapidly.

🌡 Heating and temperature

Crickets survive at room temperature, but feeding response, growth, and breeding improve in a controlled warm range.

Recommended ranges:

• Productive warm zone: 26-30°C
• Short-term holding: 22-26°C
• Cool slowdown: below about 20°C
• Avoid: sustained heat above 35°C

Use a thermostat with heat mats, heat cable, or heated racks. Heat one side or the back of the tub so the insects can move away from the warmest area.

💧 Humidity and water

The container should stay dry and ventilated, but the insects need regular moisture. Wet frass and mold are the fastest way to lose a cricket tub.

Safe moisture sources:

• Carrot, squash, sweet potato, or apple
• Dark leafy greens in small portions
• Commercial water gel for short-term holding
• A shallow dish with cotton or sponge only if cleaned often

Remove wet food before it molds. Do not mist a cricket tub as a routine shortcut; stagnant damp air encourages die-offs.

🌿 Enclosure and decoration

Use vertical egg crates to increase surface area and reduce crowding. Crickets kept in a flat pile injure each other, foul the container, and die faster.

Cleaning routine:

• Remove dead insects and old food daily when possible
• Replace wet cardboard immediately
• Keep frass dry and remove excess buildup
• Clean small holding tubs between batches
• Keep breeding tubs stable, but clean them in sections

Escape prevention matters. Sort crickets over a second bin and do not leave adults loose in reptile enclosures overnight.

🪳 Feeding

Feed crickets a dry base plus fresh plant foods. The food given to the cricket becomes part of the nutrition offered to the reptile or amphibian.

Good dry foods:

• Quality insect gut-load
• Roach or cricket chow from a reputable source
• Ground whole-grain foods in moderation
• Bee pollen or alfalfa-based insect diets in moderation

Good fresh foods:

• Carrot, squash, sweet potato
• Dark leafy greens
• Apple or orange in small amounts
• Clean vegetable scraps without pesticides

Avoid moldy food, salty leftovers, oily scraps, dog or cat food as the main diet, and food from pesticide-treated plants. Gut-load for 24-48 hours before feeding and dust according to the predator species supplement schedule.

🥚 Breeding

Breeding requires adults, warmth, food, and a removable egg-laying container. Use a shallow cup of moist coconut fiber, peat-free soil, or vermiculite covered with fine mesh so adults can lay eggs without digging up and eating them.

Basic cycle:

• Keep adults warm and well fed
• Offer a moist laying cup for 2-4 days
• Remove the cup to an incubation tub
• Keep the egg medium damp, not wet
• Raise pinheads separately with very fine food and moisture

Cricket colonies smell and crash when overcrowded. For most keepers, buying small batches and gut-loading them is easier than continuous breeding.

🩺 Common problems

Common problems:

• Mass die-off: overheating, dehydration, pesticide exposure, poor ventilation, or disease
• Bad smell: dead crickets, wet frass, rotten food, or overcrowding
• Mold: too much wet food or poor airflow
• Mites: damp waste and old food
• Escapes: loose lids, damaged mesh, or sorting without a second bin
• Predator injuries: large crickets left overnight can bite reptiles, amphibians, and invertebrates

If a batch smells sour, contains many dead insects, or came from a suspect source, do not use it for sensitive animals.

📌 Conclusion

Jamaican Field Crickets are useful feeders when they are bought or cultured cleanly, kept dry and ventilated, gut-loaded well, and offered in the correct size. Their main weaknesses are smell, escapes, disease risk, and rapid die-offs when husbandry is sloppy.

Treat feeder crickets as live nutrition. The cleaner the cricket culture, the safer and more useful it is for the animals eating it.

📚 Sources and further reading

• GBIF taxonomy: Gryllus assimilis
• CITES Appendices
• European Commission: invasive alien species
• Weissman et al. 2012: feeder crickets and densovirus