The Coal Oil Point Reserve encompasses several unique and important habitats for insect diversity. While insects as a group are only very rarely adapted to truly marine conditions, a surprisingly large number are nonetheless dependent on marine resources. One of the most important, and most conspicuous, of these resources is wrack, those unsightly piles of decaying seaweed and other marine 'junk'. Many will have noticed the enormous clouds of flies that arise from these piles when someone passes too close. Few, however, will be aware that that cloud contains several different kinds of flies, which are essentially all dependent on wrack for survival, and that that wrack pile is home to as many as a hundred other insect species that cannot survive without it.

Impressive as the wrack is, it pales in importance to the coastal dunes as insect habitat. These vegetated, mobile mounds of wave-deposited sand are where coastal diversity peaks. This results, in part, from the many plants endemic to the dunes, each of which has a host of specialist pollinators and herbivores. But the sand itself also has its denizens. Because it is loosely packed, containing much air, many insects may live most or all of their lives tunnelling through it, consuming buried and decaying plant material as they encounter it, or consuming other insects as they encounter them!

Devereux Slough, which bisects the Reserve, also represents a unique confluence of terrestrial and marine resources. The salinity of this marsh varies greatly through the year, becoming fresher with heavy winter rains, and saltier with high tidal incursions. This variability presents a severe challenge to typically salt-intolerant insects. But numerous aquatic species, from bugs to beetles, have met this challenge, surviving only in the salt marsh.

A small number of insects have even adapted to fully marine habitats. The intertidal zone of rocky beaches, so rich in marine life, also hosts several insect species. Most obvious of these are the midges that swarm over barnacle-encrusted rocks when they are exposed. The larvae of some of these midges actually enter, and are parasitic on the barnacles. Some ancestrally terrestrial predators, mainly rove beetles, have followed the midges to this very edge of what could be considered dry land, and emerge from air pockets in the rocks at low tide to hunt for their larvae.

Several other habitats protected within the Coal Oil Point Reserve, while not so intimately tied to the ocean, represent important remnants of historically more extensive habitats, such as coastal dune scrub, vernal pool, and freshwater marsh. All of these preserve a diversity of insect species once found throughout the now highly impacted Santa Barbara south coast flatlands.