Caterpillars of Pacific Northwest Caterpillars of Pacific Northwest Forests and Woodlands Handling Caterpillars Collecting Numerous techniques may be used for collecting caterpillars. Another method of search involves clipping foliage into a bag and then inspecting the foliage indoors where a microscope may prove helpful. Tools and techniques used for the collection of caterpillars include a sweep net, beating sheet, burlap skirts, funnel traps, and sifting soil. The sweep net is similar to an aerial net but used to brush over vegetation in a manner that dislodges caterpillars from their host plant. The beating sheet is held under a plant while the foliage is shaken by beating branches with a stout pole.
Caterpillars fall off the foliage and onto the sheet.
Burlap skirts can be tied around tree trunks to trap caterpillars while they are enroute between feeding sites and resting or hiding places. Funnel traps can be set under plants to collect caterpillars as they drop from the foliage. Sifting soil will result in the capture of root feeders and caterpillars preparing to pupate in the soil. An excellent means of acquiring caterpillars is to capture live adult females and rear the caterpillars from her eggs. In some species the female must be coaxed into depositing eggs by providing proper conditions of light, temperature, humidity, flying space, and a substrate for oviposition.