Editing Frass (section)

==Definition and etymology==
''Frass'' is an informal term and accordingly it is variously used and variously defined. It is derived from the German word ''Fraß'', which means the food takeup of an animal.<!--see https://de.wiktionary.org/wiki/Fra%C3%9F, like in [[:de:Reifungsfra%C3%9F]]--><ref name="OGGD">M. Clark and O. Thyen. The Oxford-Duden German Dictionary. Publisher: Oxford University Press 1999. {{ISBN|978-0198602484}}</ref> The English usage applies to excreted residues of anything that insects had eaten, and similarly, to other chewed or mined refuse that insects leave behind. It does not generally refer to fluids such as [[Honeydew (secretion)|honeydew]], but the point does not generally arise, and is largely ignored in this article.

Such usage in English originated in the mid-nineteenth century at the latest.<ref name= "isbn0-19-861271-0">{{cite book |author=Brown, Lesley |title=The New shorter Oxford English dictionary on historical principles |publisher=Clarendon |location=Oxford [Eng.] |year=1993 |isbn=0-19-861271-0 |url=https://archive.org/details/newshorteroxford00lesl }}</ref><ref name="Society1863">{{cite book|author=American Entomological Society|title=Charter and By-laws of the Entomological Society of Philadelphia|url=https://books.google.com/books?id=5m8wAQAAMAAJ&pg=PA83|year=1863|publisher=Society|pages=83–}}</ref> Modern technical English sources differ on the precise definition, though there is little direct contradiction on the practical realities. One glossary from the early twentieth century speaks of "...excrement; usually the excreted pellets of caterpillars."<ref name="JBSmith">Smith, John. B. Explanation of terms used in entomology. Pub: Brooklyn Entomological Society 1906. May be downloaded from: [https://archive.org/details/explanationofter22748gut]</ref> In some contexts frass refers primarily to fine, masticated material, often powdery, that [[phytophagous]] insects pass as indigestible waste after they have processed plant tissues as completely as their physiology would permit.<ref>Allaby (2004)</ref> Other common examples of frass types include the [[Feces|fecal]] material that [[larva]]e of [[codling moth]]s leave as they feed inside fruit or seed, or that ''[[Terastia meticulosalis]]'' larvae leave as they bore in the [[pith]] of [[Erythrina]] twigs.

Various forms of frass may result from the nature of the food and the digestive systems of the species of insect that excreted the material. For example, many [[caterpillar]]s, especially large, leaf-eating caterpillars in families such as [[Saturniidae]], produce quite elaborately moulded pellets that may be conspicuous on the ground beneath plants in which they feed. In the tunnels they eat in the leaves, [[leaf miner]]s commonly leave visible amorphous frass residues of the pulp of the [[mesophyll]]. Their frass commonly does not fill the tunnel.

In contrast, larvae of most [[Lyctus (beetle)|powder post beetles]] (''Lyctus'') partly eject their finely granular frass from their tunnels when boring in the wood on which they feed, while the larvae of most dry-wood [[Longhorn beetle|Cerambycidae]] leave their frass packed tightly into the tunnels behind them.  Many other species of wood borers also leave the tunnels behind them tightly packed with dry frass, which may be either finely powdery or coarsely sawdusty. Possibly this is a defence against other borer larvae, many species of which are [[Cannibalism|cannibalistic]], or it might reduce attacks from some kinds of predatory [[mite]]s or soak up fluids that a live tree might secrete into the tunnel.

Loose, fibrous frass of some moths in the family [[Cossidae]], such as ''[[Coryphodema tristis]]'', may be seen protruding from the mouths of their tunnels in tree trunks, especially shortly before they emerge as adult moths. In this respect, their frass differs from the powdery frass of powder post beetles such as ''Lyctus''.

Borer tunnels may occur either in dry or rotting wood or under bark, in the comparatively soft, nutritious [[Bast fibre|bast]] tissue, either dead or living.

Some boring insects do not digest the wood or other medium itself, but bore tunnels in which yeasts or other fungi grow, possibly stimulated by excretions and secretions of the insects. Such tunnels obviously cannot be permitted to become clogged, or the insects could not access their own pastures, so they must either eject at least part of their frass, or otherwise leave room for the edible growth. Examples of such boring-insect/fungal associations include [[ambrosia beetle]]s with [[ambrosia fungi]], the ''[[Sirex noctilio]]'' with its fungal partner ''[[Amylostereum areolatum]]'', and more.<ref name="Meurant2012">{{cite book|author=Gerard Meurant|title=Insect-Fungus Interactions|url=https://books.google.com/books?id=DwO5_3N7sSAC&pg=PA140|date=2 December 2012|publisher=Academic Press|isbn=978-0-08-098453-7|pages=140–}}</ref>

In a significantly different sense the term "frass" also may refer to excavated wood shavings that [[carpenter ant]]s, [[carpenter bee]]s and other insects with similar wood-boring habits eject from their galleries during the tunneling process. Such material differs from the frass residues of foods, because insects that tunnel to construct such nests do not eat the wood, so the material that they discard as they tunnel has not passed through their gut.<ref>Catseye Pest Control  http://www.catseyepest.com</ref> Even professional entomologists might need suitable instruments and detailed examination to distinguish this from food-derived frass.