Soldier flies (Diptera: Stratiomyidae) are true flies which often
superficially resemble wasps in their appearance and behavior.
Thus, they may cause some concern to homeowners. However, these
flies do not bite or sting. Adult flies are often found on
flowers and vary in color from black, metallic blue, green or
purple, to brightly colored black and yellow patterns. They can
be distinguished from wasps by the fact that they have only two,
rather than four wings. When at rest, the wings are folded
scissorlike across their abdomens. Their antennae are
characteristic among flies in having a long terminal segment
which, when bent, gives a flagged appearance. There are
approximately 1,500 species of soldier flies worldwide.
One species commonly encountered in Texas homes is Hermetia illucens (L.). These flies are active around homes and often 'buzz" residents. Frequently they are trapped inside and remain around windows seeking light. This black-colored fly is easily recognized, having two translucent "windows" on the first abdominal segment. Once this medium-sized (5/8 inch) insect is identified as a harmless fly, residents should no longer be alarmed by their presence. Outside, there is little that can be done about their occurrence. Indoors, they can be physically removed, destroyed or allowed to go outdoors. Certainly, one could use an insecticide labeled for control of "flying insects" such as aerosols containing pyrethrum, tetramethrin or allethrin. However, this practice is usually not warranted for individual harmless flies.
Larval forms of soldier flies are found in a variety of situations, but generally are in aquatic or semiaquatic habitats where they feed on algae, decaying organic matter or on other aquatic organisms. A few species are found in dung or in decaying fruit, vegetables or under the bark of rotting wood. Larvae are elongate, torpedo-shaped and may be flattened, with the skin or exoskeleton of some species firm and somewhat tough. Head is generally small and narrower than the body. The body bears no legs or other prominent features except body spines, although aquatic species may possess a rosette of hairs on the end of their bodies that is used to float on the surface of water to gain access to air and to trap air bubbles that are used for respiration while the larvae are submerged.
After development, larvae usually leave the moist or aquatic
environments in which they have developed and seek a dry place to
pupate. The larval skin of the last instar or molting stage is
used as a pupal skin in which the adult fly takes its form.
Larval forms of Hermetia illucens (L) are occasionally found indoors, particularly in bathrooms, latrines and kitchens. Larvae are discovered crawling around the floor. Apparently, these larvae have developed on algae and mold growing in proximity to leaky toilet bases and fixtures. They leave this habitat when they have completed development in search of a dry site for pupation. In the pupal stage, this insect resembles the larvae. Larval forms have also been extracted from human carrion, and there are reports that the larvae has been accidentally swallowed with contaminated food, causing myiasis.
Upon detection in homes, larvae can be physically removed. In these cases, plumbing should be inspected and repaired if slow leaks and algal buildup is detected. Insecticides are not recommended for larval control.
The USER is always responsible for the effects of pesticide residues on his livestock and crops, as well as problems that could arise from drift or movement of the pesticide from his property to that of others. Always read and follow carefully the instructions on the container label.
The information given herein is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by the Cooperative Extension Service is implied.
Educational programs conducted by the Texas Agricultural Extension Service are open to all people without regard to race, color, sex, disability, religion, age or national origin.
1989
Return
to top of page
Return
to Departmental Home Page
Last modified: March 18, 1997 by Edgar Cross