Biology

The moths are diurnally active with peaks in mid-morning and mid-afternoon.

They are most active at moderate temperatures of 20–24 degrees centigrade (Syeryebryennikov, 2008).

Life-cycle

Eggs are laid on the upper side of the primary host plant Aesculus hippocastanum. They are flattened, elliptic, approximately 0.25mm long, and whitish-translucent when laid.
The female lays 20–82 eggs (Šefrová, 2001; Girardoz et al, 2006) which hatch in 4–21 days (Šefrová, 2001; Pschorn-Walcher, 1994).

Once hatched, the larva develops a gallery mine on the upper surface of the leaf. Sap-feeding early instars are specially flattened for such a lifestyle and legless with forward-oriented mandibles.

The larva has 4 feeding instars, occasionally a fifth, developing in 20–45 days depending on the season and climate, and two non-feeding, spinning stages - one outside the cocoon and one within. A cocoon is optional for earlier generations (Šefrová, 2001; Pschorn-Walcher, 1994; Freise, 2001).

The cylindrical, normally fourth instar larva enlarges the originally circular, reddish-brown mine along the main veins of the leaf. At this developmental stage it is adapted to eat the palisade tissue of the parenchyma, damaging a surface of 4–7 square centimetres.

Pupae are 3.25–3.7mm long and up to 0.7mm wide, orange, with long wing cases and an antennal sheath nearly reaching the tip of the abdomen. The second to sixth abdominal segments bear prominent stout white spines (Deschka and Dimić, 1986; Pshorn-Walcher, 1994; de Prins et al, 2003; Syeryebryennikov, 2008).

The pupa stage lasts for 12–20 days during summer generations (Šefrová, 2001). Pupation of late summer generations always occurs in a round cocoon, and the moth hibernates during the winter in the pupal stage.

The adult head is equipped with a pronounced beak for cutting open the disc-shaped cocoon (de Prins et al, 2002), which is around 5mm in diameter.

The adult lives for a few days, and although it has a developed proboscis, there are no published observations of adults feeding.

Adults flight peaks in May, July, and August/September, with some adults appearing up to early October (Šefrova and Laštůvká, 2001).

The total life cycle lasts 6–11 weeks in the summer generation.

An increasing proportion - up to 90 percent - of each generation goes into diapause, which can last 2–3 years (Šefrová, 2001).

Cytology

The haploid chromosome number is 30 (de Prins et al, 2002).

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