Survey methods
While a number of techniques exist, we have found the following three to best suit our needs.
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1. UV flashlights
Our main method is to go out after sunset, ultraviolet (UV) flashlights in hand, in search of caterpillars that fluoresce. Many caterpillar species fluoresce when UV light is shined on them and this fluorescence is much easier to see in the dark.​
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2. Visual searches
On occasion, we do daytime sessions to search for caterpillars that feed on or within leaves (the latter are called leaf miners) or other plant parts, or that manipulate leaves in various ways to create shelters (leaf rollers/folders/tiers). On rare occasion, we have found caterpillars that feed on substrates such as fungi.
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3. Beating sheet
From time to time we sample vegetation using a beating sheet, either during the daytime or after sunset. However, we have found this method to be less productive than the other two methods.
Caterpillar fluorescing at night
Tobacco Hornworm
(aka Carolina Sphinx)
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Photo taken at night with a flash
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Same individual fluorescing under UV light