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This page was updated on
May 19, 2008

The Narrow-leaf Mountain Mahogany Leaf Miner

Lepidoptera: Heliozelidae: Coptodisca cercocarpella Braun

Narrow leaf mountain mahogany (AKA curl-leaf or desert mahogany), Cercocarpus ledifolius Nuttall., is a western US native shrub or small tree that grows in desert areas. Its use in landscaping has been limited to native plantscapes and xeriscape, but it is increasing in popularity. It is an evergreen plant in the Rosaceae. It flowers in mid April in the Grand Junction CO area, and new leaves flush shortly after flowering.

We found a leaf miner in an approximately 8 year old shrub at a native plant nursery near Clifton CO in April 2008. The mines are very distinctive as pictured below. Larvae were present in the initial collection, although more than 90% of the mines had already been vacated on the April 18 collection date. Moths began emerging in the lab during the week of May 5, 2008. The first wild-colected moths were captured in a light trap on May 19.

After initially believing this was an undescribed species, an insect taxonomist at the Smithsonian Institute found reference to it in a description published in 1925. The species, Coptodisca cercocarpella Braun, was described from a single moth reared from a pupa collected from Cercocarpus ledifolius near Logan UT. It is no known from any other published reference. The entomologist who discovered this moth, Anette Braun spent seven weeks nead Logan in 1924 on a trip to catalogue micro-moths in the area.

The type specimen was originally deposited in the insect collection at the Philadelphia Academy of Sciences, but is not listed in their index of type specimens and is presumed lost. Specimens collected in Mesa County during 2008 are deposited in the US National Museum in Washington DC, The Colorado State University Insect Museum in Fort Colins CO and the Tri River Area Extension Insect Collection in Grand Junction.

The leaf miner was initially found in this ~ 8 year old C. ledifolius planted next to a home near Clifton CO. The owners noticed the infestation when they observed small caterpillars dropping on strings from the plant. A second infestation of leaf miners was discovered in a small mature C. ledifolius planting south of Clifton.

The mines are present in the previous years leaves. These mines have been vacated. The larva cuts a near-circular exit on the dorsal surface of the leaf and then uses the cut leaf segment as a protective case.

This mine has not yet been vacated. The exit hole is visible, but the flap has not yet been cut out.

When the larva exits the mine, it uses the cut exit flap as a case. This picture shows a case still sitting on the exit hole.

The larva folds the exit flap and uses a silk strand to glue the edges together. The larvae is active within the case, but we have not observed any feeding activity while it is within it.

Larvae are about 3 mm long when the exit the mines. This is a ventral view. Legs and paired prolegs are reduced and not visible.

This picture was taken of the leafminer pupa that pupated in the lab. It is about 2.5 mm long.

Adult moths are tiny, less than 2 mm long. They are quite attractive when freshly emerged, with silvery iridescence on the proximal 2/3 of the wing and orangish coloration at the distal end. Moths emerged in the lab in mid May. They should emerge in the field after new growth on the host plant has ceased.