Dobsonflies (June 19, 2013)

Guest post by Sydney Glass, Integrated Pest Management Intern. 

The insect of the week is the Dobsonfly. Names for the larval stage include are hellgrammites, go-devils, and crawlerbottoms. The larva of the dobsonfly is used for fish bait, and many lures and artificial flies are now fashioned to look like this creature.


            The dobsonfly can usually be around 5 inches long (12.5cm) and the male has very large and sharp pinchers. The dobsonfly has wings that are usually twice as long as the body and the coloring is usually dull and mottled.


            The dobsonfly only lives about seven days once in adult form. The larval stage lives in lakes, streams, and rivers where they hide under rocks. Dobsonfly larvae live in water for a couple years, then crawl to land to pupate. Adults usually appear in late spring to mid-summer and try to stay near bodies of water so that, after mating, eggs can be laid close to the water’s edge. Dobsonflies fly at night and are attracted to bright lights, and this explains why we get so many sent for identification.


The male can grow pinchers as large as about an inch, but lacks the leverage to be able to actually break skin. These pinchers are used mostly for mating. The females, however, have short pinchers and can cause very painful bites that can draw blood. The dobsonfly is not poisonous, but will just pinch the heck out of you. When either of the sexes feels threatened, they will raise their head and spread their jaws as a warning.  In the last line of defense, the dobsonfly will emit a foul smelling spray, also not poisonous. The larva, which is predaceous, has a powerful and painful bite as well. More on dobsonflies at the Texas A&M Department of Entomology.

Dobsonfly larva. Photo Credit: Bart Drees, Texas A&M AgriLife Extension. 

Dobsonfly adult female. Photo Credit: C. L. Cole, Texas A&M AgriLife Extension.  

Dobsonfly adult female. Photo Credit: Bart Drees, Texas A&M AgriLife Extension.