Cost of running a moth trap

Following a recent conversation at a moth night and a comment on an email group I got to wondering how much it actually costs to run a moth trap overnight.

The formula is quite simple to use as long as you know the cost of a unit (kWh) of electricity. If the following is not correct then let me know, my physics is a bit rusty.

Cost  = power of lamp in kW x kWh cost x number of hours

Assuming a unit cost of 15p per kWh (which is a little on the high side but will depend on your supplier/tariff.

Cost of a 125W MV lamp per hour = .125 x 15 = 1.875 pence per hour

Cost of a 40W actinic per hour = .04 x 15 = 0.6 pence per hour

Cost of a 15W actinic per hour = .015 x 15 = .225 pence per hour

The following table summarises approximate costs for a range of running times. Values are rounded to nearest 0.5p

125W MV 40W actinic 15W actinic
Cost for 8 hours 15p 5p 2p
Cost for 10 hours 18.5p 6p 2p
Cost for 12 hours 22.5p 7p 2.5p

Personally I’ll continue splashing out the higher cost for the MV the extra moths are worth the expense :-) .


This entry was posted in Reference. Bookmark the permalink.

6 Responses to Cost of running a moth trap

  1. Raymond Watson says:

    I’ve been running a 125 mv Robinson and a twin actinic Skinner most of this year. Whilst there are more moths in total in the mv the species are very different. Some are much more numerous in the actinic and the actinic has usually been the one to turn up the unusual ones like Great Brocade, Convulvulus Hawk and Vestal. So the actinic is definately worth running.

  2. Raymond Watson says:

    Jersey Tiger was in the actinic too.

    • Tony Prichard says:

      The last line was a throw-away comment – not to be taken too seriously. Experience shows that you do get different moths attracted to the different types of light so worth running both types if you have them. It would be interesting to list those species that you have had in the MV and not had in the actinic to contrast with those in the actinic and not in the MV. Some actinic traps do attract fewer moths than MV so the odd interesting species that turns up may well stand out more in the memory.

  3. Brian says:

    As my garden has other properties nearby overlooking it, I tend not to run the 125MV all night so as not to upset the neighbours. So I run the 125 up to about midnight, switch it off and run the 40w actinic (sometimes 2 on good nights) for the rest of the night. On these longer nights such as we are having now, there are usually more moths in the actinic by dawn (if the temperature holds up) than I get in the 125 between dusk and midnight .
    So using Tony’s calculation table – if I run 3 traps at different times of the night, at the moment it costs about 15p!

  4. keith says:

    I’m just calculating how much it costs me per moth per season!!!

  5. Mark Nowers says:

    Very interesting, but I assume that there weren’t that many moths flying that night!

Comments are closed.