Insects tend to signify negative feelings and link us to primal instinctive behaviour, that of survival against all odds.
In dreams, we often translate a quality or a situation we are struggling with into an object such as an insect; psychologically, insects can represent feelings we would rather do without.
This could be something niggling at our consciences, or guilt. We may additionally be aware that we are not being treated properly and that people who should be our friends are not being fair.
To be aware of a predatory insect such as a mantis may indicate that we are conscious of trickery around us. Whatever threatens us does so on a very basic level, and we may have no defences, except those of our own nature.