Last modified: April 23, 2019, 12:44 p.m.
This is a common species in Belgium.
The larva constructs a small silken case of about 5–6 mm. The mouth angle is 0–5°.
See also bladmineerders.be.
Eggs are oviposited on the flowers. At first, the larva hides and feeds inside a seed of Juncus. A white or grey tubular silken case is constructed from August on. The species hibernates as a larva in the case and, still in the same case, pupates in May–June. The case cannot be distinguished from the one of C. glaucicollela, that has the same biology and host plants.
The adults are active from dusk till dawn and come to light.
The adults fly in June and July.
Since Juncus –the primary hostplant– prefers wet places that is also where the C. alticolella is to be found.