Naturalist Newsletter of December 31, 2007
issued from Yerba Buena Clinic just outside
Pueblo Nuevo Solistahuacan, Chiapas, MÉXICO
about 1740 meters in elevation, ± LAT. 17° 11' 27"N, LONG. -92° 53' 35"W
In the oak-pine zone below the cloudforest many broad leaves of oak saplings were ornamented with leafminer tunnels. Leafminers are the larval stages of certain insects that burrow through leaves, staying between the leaf blades' upper and lower epidermal cells. Often you can see that where the burrowing began -- where the egg hatched and the wormlike larva began eating -- the tunnel is narrow, but as the larva keeps eating it grows and the tunnel consequently enlarges. When the larva finally stops eating, emerges from the tunnel and metamorphoses, often you can see the hole left by the emerged larva.
On Christmas day I found an oak leaf with all the above evidences, and even more, as you can see below:
I can't be sure that the moth at the end of the tunnel is the adult of the larval leafminer who made the tunnel, but I think it is. One point to keep in mind is that Lepidopterids (butterflies and moths) undergo complete metamorphosis, so when the leafmining larva emerged probably it first metamorphosed into a quiescent pupa, or resting stage, before emerging as the moth.
VARIATIONS ON A LEAFMINER THEME
Leafminer tunnels are very common in many leaf types both here and in the temperate zone, but have you ever seen one branched like this one?