Guide to insects
Dragon- & damselflies
Crickets & grasshoppers
Aphids & planthoppers
Butterflies & moths
Bees, ants, wasps
Last updated 08/15/2005
| Insects of Coal Oil Point > Methods|
Makinga thorough collection of insects from an area as diverse as Coal OilPoint, while perhaps not rocket science, is more complicated than itmight first appear. It certainly requires more than wandering aroundwith a net, chasing bugs on the wing. A primary consideration is thatall of the various habitat types willhave specialist species found only in certain parts of the Reserve. Soit was necessary to spend at least a little time specifically workingin different areas. Secondly, only the most conspicuous insects can becasually netted. Most require a strategic approach, as well as awillingness to get a little dirty.
Acouple of different types of traps were used in the survey. The mostproductive for flying insects was a Malaise trap. This tent-like trap, pictured at left,takes advantage of a tendency many flying insects have whenencountering a barrier to grab it and climb. These insects arefunneled upward into a bottle of alcohol at the apex of the trap. Overhalf of the insects we report here were collected by a single Malaisetrap set in the backdune for about a month and a half in the spring of2003.
Nearthis Malaise trap, and over the same time period, we set a singleunbaited pitfall trap, shown at right. Pitfalls sample mostly flightless insects thatfall into the trap while wandering. For a short time this trap wasbaited with a substance called cantharidin. Cantharidin is a naturaldefensive chemical produced by blister beetles (their name pretty welltells the story). A number of unusual insects are attracted to livingor dead blister beetles, chewing or sucking on their bodies to obtainsome of this chemical to use in their own defense. Though we have notyet found any blister beetles at Coal Oil Point, a number of thesespecialists were nonetheless attracted to cantharidin baits (see thebeetle Notoxus lustrellus)
Collectingtechniques additionally included sand sifting, vegetation beating,aquatic netting, and wrack combing. These general techniques have beenused over a broader time frame than the trapping program describedabove, including sampling dates scattered throughout the year.
Altogetherour samples represent approximately 45 trap-days, and an additional 25person-hours of collecting effort at the Reserve. While this soundslike a lot, we estimate that we have as yet only documented somewherebetween half to two-thirds of the actual insect fauna of the Reserve.SPECIMEN PREPARATION
Thespecimens, once collected, were brought back to the lab forpreparation. While this primarily involved pinning or point mountingeach individual specimen, many required some additional attention. Mostflies (Diptera) and wasps (Hymenoptera) had been collected intoalcohol. These fairly soft-bodied insects often shrivel when simply airdried. So these were subjected to a chemical drying process using HMDS(hexamethyl disilizane), which resulted in very nice specimens. Thesecould then be glued to points. All specimens were labeled with precisecollecting data, indicating where, when and how each specimen wascollected. All 1783 prepared specimens are housed at the Santa Barbara Museum of Natural History.IDENTIFICATION
Obtainingand preparing this large collection of insects was a huge job. But itwas only the beginning. The most daunting challenge in surveying insectbiodiversity is figuring out what all has been collected. While fieldguides make identification of a few groups such as butterflies anddragonflies relatively straightforward, identification guides don'texist for the majority of insects, and those that do exist are rarelyuser-friendly. At present, we have in fact been able to identify only asmall proportion of our collection to the species level. All specimenshave been sorted to 'morphospecies', or groups of similar specimens that we believe to represent single species. But most ofthese have only been identified to the family or genus level. In somecases, we have gotten no further than 'midge' or 'tiny parasitic wasp'.This is partly a reflection of the state of insect taxonomy - even herein California, the work of specialists to fully catalog and produceguides to the fauna is far from done.
(Anyspecialists who see specimens pictured on this site that they'd like tostudy are welcomed and encouraged to contact collection curator Michael Caterino).
Disclaimers aside, a few books that we have found invaluable include:
Thegoal of this project was not just to catalog the insects of Coal OilPoint, but perhaps most importantly to be able to share thisinformation with the world through this website. In order to do that weneeded to photograph a specimen from each of our designatedspecies. The museum already had pictures of the butterflies and some ofthe beetles on hand from previous projects, however with over 600morphospecies in the collection this was still no small task.
The insects in the collection ranged in size anywhere from the sixinch Black Witch moth to the tiny .01 inch Fairyflies. As a result of our subjects' great range in sizes we had to employ several techniques to properly photograph them.Most of the specimens were photographed using a Nikon D1x.Many insects in the collection were so small that they had to bephotographed through a microscope. In these cases the Nikon wasattached to a Leica MZ9.5 stereomicroscope, shown at right. Theproblem with taking a picture through a microscope is that itonly focuses on one thin plane. For example, if the microscope isfocused on the bodyof an insect, its wings, antennae, and legs will be quite blurry. Inorder to overcome this limitation we used a technique known as 'montaging'.
A mounted insectwas positioned in clay on top of a gray board. A light diffuserfashioned out of a styrofoam cup, was placed around the specimen. Thecup was modified into a "styrofoam spaceship" with two small holes onthe side to let the fiber optic lights to illuminate the inside,and a larger hole on the top through which to view the specimen, apparatus shown at left.Several pictures were taken through the microscope. Usually 3-5 photoswere taken at various planes of focus and then saved as tiff images.These images were then imported into a photo editing program calledAutoMontage. The software incorporated the multiple images into onefully focused picture. We then manipulated thisimage in Adobe Photoshop 7.0, and converted it to the jpeg images you seeon the site.
Insectslarger than about 1 cm were photographed with the same Nikon camerathrough a macro lens. In this case, the camera was mounted above thespecimen, and mylar was used to difuse light, shown at left. In this case we were ableto take just one photo, which we then resized in Adobe Photoshop. Thismethod was used for a handful of insects in each order, for example thebees.