Much Ado About Mothing — Ben Keywood — 26Th March 2018

Moths have a bad repu­ta­tion because most people think that they eat clothes.  In fact they do not.  It is the larvae of a very few moth spe­cies that eat clothes.  These larvae prob­ably fed on the lin­ings in birds’ nests before humans wore clothes made of nat­ural fibers.  Generally moths do not lay eggs on clothes made of man-made fibers or on  laundered clothes, but, if you have an item at the back of the ward­robe  that you haven’t worn for years, it might become infes­ted with moth larvae about 3mm. long.  Sometimes people think that their car­pets have been eaten by moth larvae but it was prob­ably varied carpet beetle larvae that were to blame.

There are 2,400  moth spe­cies in the U.K. but only about 60 but­ter­fly spe­cies.  There are two groups of moths: Micro and Macro.  These are not based on size but on fam­il­ies.  About 800 spe­cies are Macro, arranged in 56 fam­il­ies.  Both moths and but­ter­flies are Lepidoptera so they are closely related.  Most moths are noc­turnal (active at night) but some are diurnal (active in day­time) and some are both.

Ben explained that moths are con­sidered to be sci­en­tific­ally import­ant because:

  • They are highly sens­it­ive to very small envir­on­mental changes so they are a good indic­ator spe­cies.
  • They are pol­lin­at­ors.
  • They are at the bottom of the food chain and, as such, are a major source of food for birds and other anim­als.

The peppered moth is a good example of how changes in the envir­on­ment can affect the spe­cies.  It nor­mally has white wings peppered with tiny black spots.  In the past, when the atmo­sphere in Sheffield was full of indus­trial pol­lu­tion and build­ings and trees were covered in soot, an all-black form of the peppered moth was common.  It was thought that the black form dom­in­ated because the white form was easily picked off by birds, but  black form moths were cam­ou­flaged and sur­vived to breed more black form moths, an example of evol­u­tion.

Moths have amaz­ing cam­ou­flage.  Many moths mimic dead leaves when they close their wings.  Some look like bird drop­pings or sticks when their wings are closed. They are also good at pre­tend­ing to be dan­ger­ous to pred­at­ors.  Some moths have large ‘eyes’ on their wings which make them look dan­ger­ous.  Some have col­oured bodies that make them look like hor­nets.  One large moth flut­ters its wings rap­idly so that it looks like a hum­ming bird.  Another has a yellow head and upper body and a ‘beak’ so it looks like a canary.

People think that moths are brown and have furry bodies, but many spe­cies are beau­ti­fully bright col­oured with very com­plex pat­terns on their wings.  Many moths are just like but­ter­flies to look at.  The green carpet moth’s wings are emer­ald green with a pat­tern like a carpet.  It feeds on bil­ber­ries on the moors around Sheffield.

Some moths have cater­pil­lars that look like sticks or pieces of wood.  The ele­phant hawk moth’s cater­pil­lar is about 10 cm. long (and looks like an elephant’s trunk) but is col­oured with pat­terns and ‘eyes’ so it looks like a small snake.  The syca­more moth’s cater­pil­lar is about 5 cm. long and has bright yellow hairs stick­ing out all round.  This seems to put off pred­at­ors.  Some cater­pil­lars are tiny — the horse chest­nut leaf miner bur­rows between two sur­faces of a leaf, eating away in safety until it is large enough to pupate.  Another cater­pil­lar, only 2 mm. long, rolls up a leaf into a tube and eats away inside it.

Ben showed a photo of his moth trap (a bright light over a funneled box) which he used to catch moths in an area of well-mowed lawns near a University Hall of Residence.  He caught many moths but they were all of one type.  He said that this was because the avail­able food suited only this moth type.  He sug­ges­ted to the Hall res­id­ents that they let the grass grow and allow other plants like but­ter­cups, dais­ies and plantains to grow in the grass.  When he set up his trap some­time later he caught sev­eral dif­fer­ent types of moths.  He said that if we want a wide vari­ety of insects (he meant moths!) in our gar­dens then we need a wide vari­ety of plants and not to spray chem­ic­als at all.

At the end Ben was asked what is the dif­fer­ence between moths and but­ter­flies.  He admit­ted that, in fact, there is no real dif­fer­ence.           This was a fas­cin­at­ing talk with so much new inform­a­tion that I’ve only scraped the sur­face.