Back to the Teacher Pages News | Resources | Calendar | Teaching Activities | EEK! Home


A Guide to Frog Egg Identification and Metamorphic Timing

Frogs are selective and only breed when temperatures in the air and water are just right. This means that their breeding times are not exact and will be different each year. To make things a little more interesting, the number of eggs laid, shape and size also varies between species. This is also true for the metamorphoie process for each species. This is a guide to frog egg identification and metamorphic timing to help you in this activity.

Wood Frog
Egg Identification: Breeding in March-April. Large globular mass, 60-100 mm diameter, attached to submerged plants, near water surface, 500-800 eggs per mass, dark colored. Note: all wood frogs in ponds lay eggs together in same part of pond.
Metamorphosis: Eggs take 15-20 days (depends on water temps.) to hatch. Tadpoles metamorphose in 1 ? - 2 months.

Western Chorus Frog
Egg Identification: Breeding in late April-early May. 20-100 eggs .5-1.3 mm, wrapped around grass or twig 8-20 cm under water in small cylindrical mass 10-20 mm x 30-40 mm.
Metamorphosis: Eggs hatch 6-18 days. Metamorphose 1 ? - 2 months after.

Northern Spring Peeper
Egg Identification: Breed April-June. Eggs masses have 800-1,000 small white eggs, 1 mm diameter singly or clustered in 2 or 3 attached to grass or vegetation.
Metamorphosis: Eggs hatch in 2-3 days. Tadpole transforms in late May-early June when 8-15 mm long.

Northern Leopard Frog
Egg Identification: Breed in April. Female lays black eggs in a tight globular mass, 10-16 cm in diameter, of up to 6,000 in number. Eggs measure 1-1.8 mm. Eggs are laid several centimeters under water on vegetation.
Metamorphosis: Eggs hatch in 13-20 days. Metamorphosis occurs in late June-mid July, approximately 70-100 days.

Pickerel Frog
Egg Identification: Breeding takes place in April-May. Eggs are light brown, 2 mm diameter, laid near the water surface on vegetation. Eggs are found in loose globular masses 90-100 mm diameter.
Metamorphosis: Tadpoles hatch in 12-18 days and metamorphose in 60-80 days.

Eastern American Toad
Egg Identification: Breed in May. Eggs are found in long strands 10-15 mm wide and several meters long with 4,000-8,000 eggs.
Metamorphosis: Eggs hatch into tiny black tadpoles in 2-8 days. Metamorphosis occurs in late June or early July (roughly 2 months), maturity takes 2-3 years.

Eastern Gray Treefrog
Egg Identification: Breed in April to early July. Females lay up to 2,000 eggs singly or in loose clusters of up to 30 eggs attached to vegetation near the surface.
Metamorphosis: Eggs hatch in 3-6 days and tadpoles metamorphose in 6-8 weeks.

Cope?s Gray Treefrog
Egg Identification: Breed from May-June. Females deposit 10-40 eggs at 1.1-1.2 mm diameter in loose clusters attached to plants or floating on the water surface.
Metamorphosis: Information not available.

Blanchard?s Cricket Frog
(protected species-avoid collecting their eggs)
Egg Identification: Breed in May-June. Females lay 200 eggs each 2-3 mm in diameter. Eggs attached to vegetation in flowing water on the water surface in clusters of 10-15 each.
Metamorphosis: Tadpoles metamorphose in early August.


Mink Frog
Egg Identification: Breed in June and July. 2,000-4,000 brown-black eggs are laid in a loose globular mass, 75 x 125 mm, attached to submerged plants at about 1 meter below the surface.
Metamorphosis: One year.

Green Frog
Egg Identification: Breed in mid May-July. The egg mass is a thin film 30x30 cm with 1,000-4,000 eggs measuring 1.0-1.5 mm each in diameter. Egg mass floats on the surface.
Metamorphosis: 70-85 days.

Egg Identification: Bullfrogs breed mid May-June. Black and white colored eggs, measuring 1.2-1.8 mm diameter, are found in masses of 1,000-5,000 eggs. Masses measure 60 cm x 30-60 cm and are laid as a large surface film several layers thick.
Metamorphosis: Tadpoles metamorphose in July and August of their second year. Young frogs take 2-3 years to mature.

Vogt, R.C. Natural History and Ecology of Amphibians and Reptiles in Wisconsin. 1981. The Milwaukee Public Museum, Milwaukee, WI. 205pp.

Back to Teaching Activities

Back to the Teacher Pages News | Resources | Calendar | Teaching Activities | EEK! Home
Workshop and Events Calendar Go to the DNR Homepage Teaching Activities Educational Resources What's New for Teachers Back to the Teacher Pages Index