Iris Leaf Miners

Cerodontha iridis (syn. Dizygomyza iridis) is found is found in France, Germany, Hungary, Italy, Portugal, and the UK. It is an uncommon fly whose larval stage feeds on Iris leaf tissue by making mines (or tunnels) as it consumes the tissue. The fly will continue to develop and eventually will morph into a dark-brown pupa. The adult emerges, exits the leaf, mates, and lays eggs on top of other leaves. There are at least two generations a year. The first generation emerges from winter dormancy (as pupae) in April or May. The next generation emerges in June or July.

Infected plants are easily diagnosed by the mining patterns of photos 1 and 2. Tunnels of this species often contain multiple larvae feeding together. Damaged tissue have a mottled green appearance. The pupae are situated perpendicular to the leave length at the lower end of the tunnels. Susceptible plants include I. crocea, I. ochroleuca (syn. I. orientalis), I. spuria, I. foetidissima and their cultivars.

It has one known natural wasp parasitoid, Hemiptarsenus unguicellus.

Photo 1 shows the damage patterns of the leaves. Photo 2 shows the tunneling patterns, including pupae at the bottom of the tunnels. Photo 3 shows the larval stage of the fly and image 4 shows the pupal stage. Photos and leaf dissection contributed by Janos Agoston.

Cerodontha iridis, Janos AgostonCerodontha iridis, Janos AgostonCerodontha iridis, Janos AgostonCerodontha iridis, Janos Agoston

A related species Cerodontha iraeos is also reported to specialize on irises. It's tunnels are short and whitish. The dark pupae can be found inside the mine. The flies are active during summer. Its hosts include Iris pseudacorus and Belamcanda. Natural wasp parasitoids include Chrysocharis polyzo, Hemiptarsenus unguicellus, Pediobius metallicus, Merismus megapterus.

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