Preserve larval stages of insects and other soft-bodied specimens immediately by dropping them directly into a 70 to 90 percent ethyl or isopropyl alcohol solution. When collecting in the field, carry a few small vials of preservative fluid to store specimens.
An even better method of preserving caterpillars, grubs, and maggots, is to carry them home alive in separate plastic or glass containers, then submerge them for 1 to 2 minutes in boiling water. After this they can be immediately placed in the vials of alcohol. This process kills bacteria in the digestive tract and prevents discoloration. After a day or two, the liquid may become discolored. When this happens, transfer the specimens permanently to fresh alcohol solution.
Specimens in vials must be labeled exactly as described for pinned specimens with two exceptions. Labels must be written with a soft-lead pencil or with India ink so that the writing does not disolve or run. Only one label should be used, thus append any information such as host and identification to the bottom of the label. Cut labels longer to allow for this. Labels must be included with the specimen inside the vial. Do not attach them to the outside as this has proven to be an unreliable method of labeling.