We have often come across leaves that look as if someone doodled squiggly lines on them. These squiggly lines are in fact the action of a species of insects known as leafminers. Not all leafminers zig-zag their way through leaves. They also cause damage in the form of a whitish transparent blotch. Blotchy leafminer damage is often mistaken for some type of disease. These insects infest plants and trees, which could make them unsightly and weak. As the larvae feed they consume the plant tissue leaving clear mines that, when they die, turn brown and crispy. Usually by the time the damage is observed, the larvae have already left the leaves and are pupating underground.
The damage done by these garden pests to our plants is easy to spot because of the “mines” created as the bugs chew inside the leaf. In some instances the leafminer will cause a light colored blotch on the leaf, in really bad cases the plant will look discolored and/or drop leaves. It is rare that leafminers do enough damage to kill a plant, what they destroy mostly is the aesthetic value of your ornamentals for a short period of time. Found in greenhouses, home gardens and landscaped areas across the country, leafminers are the larval (maggot) stage of an insect family that feeds between the upper and lower surfaces of leaves. On heavily infested plants it is not uncommon to find 6 or more maggots per leaf. Although damage can restrict plant growth, resulting in reduced yields and loss of vigor, healthy plants can tolerate considerable injury. Host plants include beans, blackberries, cabbage, lettuce, peppers, and a variety of ornamental flowers, trees and shrubs. And in the case of such vegetables grown for their leaves, like spinach, chard and beet greens, leafminers can mean a loss of a crop.
Leafminers are insects that have a habit of feeding within leave s or needles, producing tunneling injuries. Several kinds of insects have developed this habit, including larvae of moths, beetles, sawflies and flies. Most of these insects feed for their entire larval period within the leaf. Some will also pupate within the leaf mine, while others have larvae that cut their way out when full-grown to pupate in the soil. Injuries caused by leaf and needle mining insects can superficially resemble symptoms produced by leaf spotting fungi or other abiotic problems. They can be differentiated by pulling apart the blotchy area. If damaged by insects the leaf or needle will have a hollow area and may expose either the insect and/or its droppings. Leaf spotting fungi cause these areas to collapse, without any tunneling.
The article given below will further explain the damage caused by these leafminers.
Locust leaf miner cause of browning roadside trees
July 31, 2014
By Rebecca Finneran
Dramatic browning of black locust, a common roadside tree in the lower peninsula of Michigan is being caused by a small leaf-mining beetle (Odontota orsalis.)This small (one-eighth of an inch long), colorful beetle deposits eggs inside black locust leaves where the larvae feed, creating leaf mines that eventually turn the leaves brown. Heavy infestations cause entire trees or groups of trees to turn brown.
“If this has happened to trees on your property, don’t panic and cut them down,” says David Smitley of Michigan State University Extension. Late season browning or defoliation may weaken trees, but it rarely kills them.
Infestations tend to be every couple of years but one site in Grand Rapids, Michigan has had the damage nearly every year with no ill effect to the trees themselves. With a native range from Pennsylvania to Georgia, black locust is a very adaptable plant with dense hard wood that will survive even the toughest conditions. It can be easily found in Michigan and older stands can be quite beautiful when in bloom.
Although injuries produced by leafmining insects can be unattractive, it is rare for them to significantly affect plant health. Also, most leafminers have important natural controls which normally check populations before too much injury is done to plants. Therefore we need a solution that helps protect our plants and trees from damage, while at the same time does not harm the environment in any way. So, how do we fight this pest? Keep reading!
At C Tech Corporation, we offer a safe and foolproof solution to deal with these tiny insects. Termirepel™ is a non-toxic, non-hazardous product that primarily repels insects from the application. It is a broad spectrum repellent which works against almost 500 species of pestering bugs thus efficaciously fending them away from the application. The best feature of this product is that it is environmentally safe and causes no harm to the insect as well as humans and the environment. It is available in masterbatch and lacquer form, and as a liquid solution. To keep these insects at bay, this product can be coated on the tree trunks in lacquer form. The repelling mechanism of the product would ward off the blue ash aphids and any other insect that could harm our trees.