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BEATING or SWEEPING for LARVAE
A MOST PRODUCTIVE COLLECTING TECHNIQUE
In addition to simple DIURNAL and NOCTURNAL searching for larvae, beating or shaking plants over a sheet or other piece of material spread on the ground (or held up more closely beneath the branches), will often reveal the more cryptic (hard-to-see) larvae, that are usually missed during simple searching or scanning of the vegetation. “Beating-sheets” (or trays) are offered by various suppliers of entomological equipment (such as BioQuip, for example) - OR, you can easily make your own. There are various shapes and designs, depending upon your preferred or usual method(s) of collecting (see books or other links for illustrations)....There are a few specific points I'd like to make here - rarely (if ever?) mentioned by others: Regarding the best material to use - a rough, NOT smooth surface, is much to be preferred for most moth larvae, as the highly cryptic twig or stem-mimics will often “clamp”onto the textured surface, while you are tipping the debris from side-to-side on the tray. On a smooth surface, they CANNOT cling, and are likely to be tipped out (motionless and unseen) along with the debris, as you search through it. Given the choice, dislodged larvae are often quick to grab ahold of any surface that they have fallen upon - the more so if the debris is gently shaken and tipped back-and-forth across the tray a few times. The instant they clamp onto the (rough/textured) canvas or other surface of the beating tray, they are rendered more readily visible, while the debris is being carefully tipped off the tray in small increments, and they will typically remain behind (clinging)....Slippery or smooth materials will NOT permit them to do this....(useless)!! TRUE, a textured surface also means that the debris or litter will adhere to some extent, when you are attempting to tip it out, but this is a minor annoyance when contrasted with actually missing some of the larvae by “throwing out the babies with the bathwater”!!....
And yes indeed, there are some cryptic larvae that will “play dead” or remain still, and therefore won't cling to the tray surface immediately after dislodgement (although they may do so later....). However, there is a simple solution to this problem, although I've never seen (or heard) it mentioned elsewhere. This brings us to the next topic: What is the ideal color for the beating-tray material??
BLACK is far preferable to white, for two major reasons, IF it is lepidopterous larvae that you are seeking: (1) Bright white may soon give the collector “ snow-blindness ” on a sunny day; I find this extremely annoying in brightly sunlit localities! (Yes, I know, there are sunglasses to be had....). Of course, this is not a problem during cloudy or foggy weather - or, at night. But far more important (and very useful), is the fact that (2) a black or other dark surface HEATS UP quickly in warm and sunny weather. So, guess what this causes those aggravating cryptic larvae (that often remain motionless upon hitting the tray) to do??....They will immediately begin to “dance” - or, at least to start actively crawling about, in a desperate attempt to escape the “hot-seat” - thereby QUICKLY revealing themselves to the collector! You will NOT reap this dividend if your tray is white, or of any other palecolor that fails to heat up in direct sunlight....
I hasten to add that black is NOT being recommended (as a beating-tray color) for any of the various insect orders that are capable of flight (or hopping), such as Heteroptera, Homoptera, or many beetles, etc.. But, as larvae are not capable of flight, the black “hot-seat” can lead to much greater efficiency in the field - not to mention the elimination of “snow-blindness”!!
Having said all of the above, I fully expect that (most of) the commercial suppliers will just continue to mechanically crank out uniformly SMOOTH and WHITE beating-trays, exactly as always before....[Probable “reason” to be given?? - “Because we've always done it that way”!!]....OR, perhaps because white is the cheapest and/or easiest to obtain, in most commercially available materials??. (Great reasons !!?) Default to the “Education ” cartoon; also applicable at this point may be my all-time favorite quotation from Herbert Spencer?
Tennis racquets and/or table-tennis “paddles” make excellent beating devices, where smaller shrubs or clusters of foliage are involved. For the heavier branches of trees or large woody shrubs, a stout axe-handle or baseball-bat can be used, but care must be taken to avoid hitting so hard that the larvae are catapulted beyond the borders of the sheet or tray!....See also the notes on a special type of collecting-method (the “twist-&-squeeze technique”!) that can be very effective for revealing cryptic larvae on certain types of flexible plants: click here for chapter-&-verse. See also p.324 (col's. 2 + 3) of the same book for additional tips on locating cryptic larvae that cannot be collected either by beating OR sweeping....Burlap-wraps loosely tied around tree trunks, and oards placed on the ground under trees and bushes etc., are other ways to obtain nocturnally active larvae that hide by day.
Sweeping nets should have a relatively short (± 3-4 ft.), very sturdy handle, and a heavy steel frame or hoop; the bag should be of canvas, or other heavy-duty materials, that won't rip when being swept or dragged through the vegetation. This device can be used for finding larvae that hide and feed upon flexible, grassy or weedy (herbaceous) vegetation, where "beating" is difficult or impossible. Again, both diurnal and nocturnal sweeping are worthwhile particularly the latter. Many of the larvae occupying this niche hide by day, low down on their foodplants, or buried in leaf-litter and debris beneath the plants, and they will only crawl UP the plants to feed after dark ....
Growing Up Wild in Beverly Hills!
EARLY DAYS on OAK PASS Rd. (1937-1945) and HOW the ROAD GOT ITS NAME
- (A) Botanical Highlights
-- Historical Remarks on Oaks
-- EARLY EVOLUTIONARY STAGES of the "SMOG-DENIAL SYNDROME"!
-- OAK PASS NATIVE PLANTS TODAY (??)
-- Echos From the Past!
-- A Bit of SUMMERTIME FOGBANK-BOTANY
- (B) LOCAL BUTTERFLY HIGHLIGHTS
- (C) LOCAL BIRDS REMEMBERED
- (D) LOCAL MAMMALS REMEMBERED
- (E) REPTILES & AMPHIBIANS REMEMBERED
DESSERT (Purely for Amusement!)
THE HONEY-SNOB'S CORNER
A five-year study (1953-1957) documenting the occurrence of 283 macro-moth species on one acre of woodland habitat at 9601 Oak Pass Rd., 5 road-miles north of Sunset Blvd., Beverly Hills (a mixture of undisturbed Southern Oak Woodland / Chaparral / Coastal Sage Scrub habitat, at 1100 ft. elevation).
WHAT TO EXPECT AT THIS CALIFORNIA SITE
ABOUT THE BACKYARD CONCEPT
BACKGROUND & INTRODUCTION
About the Moth Studies at 9601 Oak Pass Road
BEATING or SWEEPING for LARVAE - A MOST PRODUCTIVE COLLECTING TECHNIQUE
The OLD BEVERLY HILLS (OAK PASS ROAD) MOTH STUDY COMPARED WITH THREE OTHER (MORE RECENT) SURVEYS IN COASTAL SOUTHERN CALIFORNIA
OBSERVED DIFFERENCES IN THE MACRO-MOTH FAUNAS OF THE ABOVE THREE OTHER SURVEYED COASTAL CALIFORNIAN LOCALITIES
HISTORICAL PHOTOS and A PLEA for FUTURE STUDIES in the SAME REGION
FRANK SALA'S CORNER
FRANK HOVORE'S CORNER
1C - HABITAT PHOTOS (1957-1964)
Copyright ©2005-2011 Noel McFarland. All Rights Reserved.