Emerald ash borer has now been found in Connecticut – specifically, in sections of New Haven County. These pages have been assembled to assist arborists and others in the identification of the emerald ash borer, and in being prepared for dealing with this insect.
The emerald ash borer is a highly mobile insect that has a history of establishing rapidly into new areas after being introduced. The most common means of introduction are the movement of infested logs, firewood and nursery stock. For those reasons, it is important to be aware of the potential to move the insect, and to comply with all regulatory efforts to limit that spread. In particular, the quarantine to be placed on movement of material out of New Haven County should be followed.
Also Note: If you do find Emerald Ash Borer, you must report your find to the Connecticut Agricultural Experiment Station. EAB is an insect of federal regulatory concern. You may report your find by sending a digital photo via email or by calling the Station. The email address is CAES.StateEntomologist@ct.gov. The phone number is 203-974-8474. Include any information that would be helpful to finding the site (GPS coordinates, street address, etc.) DO NOT MOVE EITHER THE INSECT OR THE WOOD FROM THE SITE!
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Certainly, removing the ash tree, whether or not it is infested with emerald ash borer, is one way to deal with the issue. Removing an ash tree and then replanting with another, non-susceptible species allows a client to escape concern about future expenses should emerald ash borer be found in the vicinity. Particularly if a tree is in poor condition or is not highly-valued, this option might be appealing.
Removal of ash trees can also be a part of a strategy to slow the spread of EAB. Reducing the number of ash trees available to the insect reduces the number of opportunities for the developing EAB population, and might even play a role in causing a growing population to be steered away from moving in a certain direction.
It is important to note, however – it is very unlikely that the Federal Government will mandate the removal of ash trees in Connecticut. EAB is now considered to be established in North America, with eradication of the invasive pest no longer possible. As a result, there is no reason to pursue to large scale removal of host trees, such as is still being done with such other insect pests as the Asian longhorned beetle.
The use of trap trees is usually seen as more of a monitoring tool than a control method. However, there is the potential to use trap trees as part of a control strategy, if the trap trees are used to draw in emerald ash borer adults, which would then be destroyed through the felling of the tree, use of a systemic insecticide or other means. Even felling the tree and bucking it up to hasten dessication will greatly reduce the number of EAB that will emerge from the tree during the next year.
Pesticides may be used in the effort to control the emerald ash borer, including by arborists seeking to protect landscape ash trees for a client. In fact, such uses are being encouraged by many people who see the use of insecticides as a way of allowing ash trees to survive the initial wave of EAB infestation, thus giving the various ash species a greater opportunity to become reestablished, particularly if natural checks and balances provide improved opportunity for ash survival in the future.
An excellent summary of insecticide options is available on line through the following link:
Insecticide Options for Protecting Ash Trees from Emerald Ash Borer. This publication discusses both systemic and foliar pesticides and how effective they are in the control of EAB. Three systemic insecticides are specifically discussed – dinotefuran, imidacloprid and emamectin benzoate. Both trunk and soil applications of these systemics are considered.
The authors of this publication are very careful to discourage the application of pesticides for the control of EAB until the beetle is known to be in close proximity to the trees being treated. They recommend that ash trees not be treated unless those trees are within a county already quarantined for emerald ash borer, or within 10-15 miles of the border of a county that has already been quarantined. According to this recommendation, there is no need to treat ash trees in Connecticut yet for EAB.
The authors also indicate that already infested trees that are not too heavily damaged can be effectively treated with a systemic insecticide. As there is no mandate to remove trees found to have EAB present in them, this give tree owners a little more latitude with respect to their options as the search for the beetle continues.
At least one native braconid wasp, Atanycolus cappaerti, is known to parasitize the emerald ash borer. In EAB’s native range, in northeastern Asia, at least 3 different wasps are known to be parasitoids of EAB and are being considered as potential North American biological controls.
The experience in Connecticut with the hemlock woolly adelgid and the gypsy moth suggests that, if the host threatened by the invasive pest can survive the initial wave of infestation, biological controls along with natural checks and balances can work towards mitigating the effects of the invader.
Slowing the spread of the emerald ash borer is more of a strategy than a technique, and is one that is apt to involve a whole series of techniques. For example, one approach to slowing the spread of emerald ash borer might be the removal of large ash trees, particularly large trees in either an undesirable condition or location, so as to reduce the amount of phloem tissue for the insect to feed on. At the same time, other nearby trees could be turned into trap trees, to collect a certain proportion of other active adult beetles in the vicinity. Finally, insecticides could be used, both to protect certain desirable trees and also to further reduce the adult population, through their feeding on the treated foliage. These desired trees could then be maintained over a period time, to help reestablish the ash population after the first wave of beetles has passed through.
For a more detailed discussion of this concept, please go to the paper by:
The Coalition for Urban Ash Conservation
The best advice is to keep firewood local.