Hi Edwin, I have been studying leafminers for several years, and have read all of the relevant North American literature I can get my hands on. Some authors apply the term "mining" to any internal plant feeding, but when people are being precise, this term applies to feeding that is externally visible, i.e. just beneath the epidermis. So just about any internal leaf feeding is referred to as leafmining, although there are feeders in thick leaves of agave that would more properly be called borers. Feeding in larger veins, the midrib, and the petiole can be either mining or boring by this definition. Among stem feeders, there is usually a clear distinction between stem miners and stem borers. Virtually all stem mines are made by groups of insects that are primarily leafminers (mainly Diptera: Agromyzidae and Lepidoptera: Gracillariidae), whereas all sorts of other things can be stem borers (feeding in pith / inner tissues). With woody plants, bark mines are not always externally visible, but they are strictly in the bark, whereas borers feed partially or entirely in the wood.
There are very few gall inducers that are properly called miners, because mining refers to active excavation of tissue, whereas most gall inducers are just passively sitting there, sucking the juices provided by the modified plant tissue. I've discussed this with Ray Gagné, the North American gall midge (Cecidomyiidae) expert, and he says the mouthparts of gall midges do not allow them to excavate tissue as a leafminer does. So "boxwood leafminer" is a misnomer; midge-induced blister galls are created by the plant's reaction to the insect, and the larva just moves around a little within this pre-defined space. Sawfly gallmakers chew up the insides of their galls, but that definitely isn't mining. There are a few leafminers whose mines become galls, but once they start eating the inside of the gall, they aren't really mining anymore. The German leafminer specialist E. M. Hering's (1951) Biology of the Leaf Miners defines mines as feeding channels caused by insect larvae inside the parenchyma or epidermis tissues of plants, in which the epidermis or at least its outer wall remains undamaged. He states that mines can be made in leaves as well as in the green parenchyma layer of fruits, stems, or roots. Hope that helps! Charley On Thu, 12 Jan 2017 13:56:53 +0000, Edwin Cruz-Rivera <[email protected]> wrote: >Dear Ecologgers, > Many insects that dig into plant leaves are collectively called "miners", "plant-mining insects", or other derivations of the term. Similarly, there are some marine isopods that dig into seagrass leaves for which the term has been applied. This seems to be a fairly arbitrary term. For example, gall formers are sometimes called miners, but stalk borers are referred to as such and not as miners. Looking at a couple of reviews, I have not been able to find a functional definition of what constitutes a "miner." Is there such a thing? My background is not terrestrial and there may be older literature I have not found defining the term. >Hope you have a productive 2017, > >Edwin >================= >Dr. Edwin Cruz-Rivera >Associate Professor >Department of Biological Sciences >University of the Virgin Islands >#2 John Brewers Bay >St. Thomas 00802 >USVI >Tel: 1-340-693-1235 >Fax: 1-340-693-1385 > >"It is not the same to hear the devil as to see him coming your way" >(Puerto Rican proverb) > >
