Chironomid midge- Matt Bertone, NC State

The Maryland Department of Agriculture in conjunction with Maryland Department of Natural ​Resources established the Midge Suppression Pilot Program via Executive Order in 2017.  The purpose of the pilot program is to test the feasibility of Back River midge control and determine the impact of Bacillus thuringiensis israelensis (Bti) in controlling midge populations in the area. The pilot program also aims to determine the most cost effective dosage and frequency of Bti treatments in the area. 

What are midges? 

Non-biting midge flies or chironomids commonly occur in inland and coastal natural and man-made bodies of water. These midges are commonly known as “blind mosquitoes” because they are mosquito-like but do not bite. Midges are also called “fuzzy bills” because of the male’s bushy antennae. 

These aquatic insects are tolerant of a wide range of environmental conditions. Chironomid midges are found in swift moving streams, deep slow moving rivers, stagnant ditches, and in lakes and ponds that are rich in decomposing organic matter. The presence of certain chironomid midges is often used as an indicator of water quality. Bodies of water in urban and suburban areas are subjected to intensive human use through residential, recreational and agricultural activities. Through runoff, these ponds and lakes often become exceedingly rich in nutrients. 

Consequently, the variety of organisms in such habitats is usually low with just a few pollution tolerant species developing large populations. Some species of chironomid midges that are tolerant of low dissolved oxygen conditions often are a major component of the bottom invertebrate organisms of urban and suburban lakes, ponds and storm water retention ponds. (Credit: North Carolina State Extension)

 

How are midges treated in this pilot program? 

​Bacillus thuringiensis israelensis (Bti)​ is applied by boat and/or helicopter using an apparatus designed specifically for midge control. Bti is a naturally occurring soil bacterium that has been demonstrated to be non-toxic to humans, mammals, birds, fish and most invertebrates. 

Is BTI safe? 

The pesticide, Bactimos WG, was chosen because of its effectiveness for this use and because it is only harmful to a very limited variety of organisms including midge larvae, black fly larvae, mosquito larvae and a few other aquatic Dipteran (flies) insects. It is not harmful to humans, fish, crabs or other aquatic invertebrates.