Hi Joey –
Tachinid flies are often under appreciated for their work controlling greenhouse and garden pests. They look rather like a normal household fly, however they come with devastating news to any insect that is munching on your plants. Depending on the subspecies, they can deposit their eggs on leaves that will in turn be ingested by the host, they can glue the egg on to the host, or they can inject the egg inside their host. Once the egg hatches (typically takes 3-4 weeks to hatch) it will start to consume the host.
Tachinids are so beneficial because they have a wide diversity of prey, ranging from gypsy moths, cabbage loopers, Japanese beetles, army-worms, cutworms, sawflies, codling moths, peach twig borers, pink bollworms, tent caterpillars, squash bugs and “many others”. When beetles are the host, both the larva and adults can be parasitized (depending on tachinid species). Adults in the true bug and grasshopper orders are subject to parasitism.
Research is still on going, but there seems to be a cutworm type that has been shown to reduce populations of the variegated cutworm, the army worm and the yellow-striped army worm.
Since Tachinids are not commercially available, the best way to get them in your garden is to grow plants with umbel-type flowers (carrots, cilantro, dill, coriander, buckwheat and sweet clover).
Hope this helps!