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Seven Backyards
Moths...Moths...Moths...and their Habitats...and other stuff....
Several Long-Term Backyard
Studies in the U.S. and Australia


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Beating or Sweeping for Larvae
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 other links for illustrations)....There are a few specific points I'd like to make here - rarely (if ever?) mentioned by others:

Regarding 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 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 soon gives 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 pale color that fails to heat up in direct sunlight....

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 at this point.]

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!!

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 boards on the ground under trees and bushes etc., are other ways to obtain nocturnally active larvae that hide by day.

Seven Backyards

Preface

OVERVIEW

Moths and Memories

Dedication

Where Are the Specimens Now?

ASH CANYON FIRE (2011)


Background and Introduction

Elfin Forests, Worldwide: MAQUIS / FYNBOS / KWONGAN / MATORRAL / CHAPARRAL

About The Backyard Concept

Motivations: Why Publish This Material?

Summarizing How These Projects Evolved

About the Photographs

Bias in Photo Representation

Moth Identifications

Taxonomy & Classification (the names)

About Moth Families & Subfamilies

Some Thoughts About Moth Surveys

Abundance Ratings Defined (8 Categories)

About the Flight Periods

Interpretation of the Flight-Phenograms

Miscellaneous Comments on Black Lights

Peculiarities of Moth Activity

Prime Time = Full-Moon-Plus-Ten

How To Obtain Perfect (Moth) Specimens

To Kill Or Not To Kill??

Beating or Sweeping for Larvae

ACKNOWLEDGEMENTS & DETERMINATIONS

Miscellaneous Tidbits Dept.

PHOTO CREDITS