A light-proof rearing container is an excellent tool for collecting insects. Because it allows removal of insects directly from the pieces of substrate that they are using, the collector can determine specific habitat associations for insect species. Small specimens that would be difficult to remove by hand from dead wood or other material are also concentrated in the container's collection bottle.
You will need the following materials and equipment to build one container:
This series of steps should be performed by an adult. It is important to wear safety glasses while drilling the holes. You will drill three holes in the pail and one in the beverage bottle.
Clean the pail thoroughly with dish soap or other mild detergent before starting (this pail contained hydraulic oil and was difficult to clean). Proceed by marking the hole locations. The holes in the pail should be ten centimeters from the bottom--one on each side, with a third in between.
The beverage bottle should have a single hole drilled near the middle of its side. Do not drill the hole completely through the side of the beverage bottle, but instead just use the bit to carefully score the plastic and then complete the cut with a utility knife.
The holes in each side of the pail will permit ventilation. By covering them with black cloth (below left), you will be able to maintain lightproofness. Cut two square pieces, each two inches by two inches. Secure them tightly over the holes with the electrician's tape. This pail had a fitting in its lid used to pour the hydraulic oil. The fitting was removed and the hole was also covered with black cloth. A rubber band held the cloth in place (below right).
Push the PVC fitting through the middle hole from the inside of the pail. The hole in the beverage bottle should fit snuggly over the fitting from the outside of the pail. If either of the two holes are too small to accept the fitting, they can be slowly enlarged with sandpaper.
The picture at below right shows some pieces of dead wood that were collected in the field. The collector cut them to a size (~30cm) that will fit into the rearing container. The collector also carefully documented collection date and location and wrote this important data on a piece of masking tape affixed directly to the pail. Because this collector was interested in habitat information for insect species, she cut all of the pieces from the same dead fallen limb.
Carefully monitor conditions inside of the pail, especially for the first couple of weeks of rearing. If you observe excessive condensation inside of the pail you can put a short stack of dry paper towels inside in order to absorb excess moisture. It is also important that the material inside of the pail does not become excessively dry. The log pieces should feel slightly moist to the touch. If you maintain the container for more than a few weeks you can expect a significant amount of evaporated water to escape through the ventilation holes. Replace water in small amounts if you observe the material drying out.
You will need a few additional items in order to collect and preserve your insect specimens:
Specimen storage bottles should be prepared ahead of time. This one contains some 70% isopropyl alcohol preserving fluid, along with a label with all of the substrate collection information written in pencil.
The beetle at above right was introduced into the rearing container as a larva more than a month ago. When it emerged as an adult it was attracted to the light coming through the single hole in the side of the pail, which communicated directly with the collection bottle. This animal will pour out of the bottle and into the storage jar where it will be quickly killed by the preserving fluid. Flying insects, such as wasps or flies, may be more difficult to remove. Such animals can be subdued by squirting some alcohol preservative fluid into the jar through its open lid. After pouring specimens killed in this manner into the storage jar the collector should allow the preservative fluid to evaporate before re-affixing the collection bottle.
Animals that appear as though they might be able to sting, such as wasps or ants, can also be killed before removal by squirting the alcohol solution into the collection bottle.
If you check and empty the collection jar frequently you should be able to collect the specimens in excellent condition. If you begin to notice damage to the specimens (because they are dieing and decomposing, or eating each other) then you might want to add a killing/preserving agent to the collection bottle. Alcohol will evaporate very quickly. The bottle pictured above contains a concentrated (1:15) brine solution (45 ml water + 3 ml table salt + 1 drop dish detergent). The detergent serves as a wetting agent that causes the specimens to become soaked and sink into the solution more quickly. If you use a salt solution as a killing agent the specimens should be soaked in plain water for one hour before being placed in the alcohol preservative mixture.
Specimen collection is just the first step in a series of fascinating activities that can be used to explore the biology of insects. Further processing, such as mounting on pins and individual labeling of specimens, can help to improve the usability of specimens, making it easier to handle them and make identifications. s
