Facts: Ichneumon wasps are very common but easily overlooked. They range in size from about 1/4 inch to over an inch. They come in many colors but often are black with yellow markings or brown. They can often be found around light at night or near wood piles where they are searching for borers that they used as food for their larvae. They are parasitic wasps that sting the prey and leave eggs in the prey. The larvae develop inside the host and emerge later.