Not just moths – other insects in light traps

Nicrophorus investigator, one of several burying beetles that is regularly attracted to light

Light-traps are for catching moths aren’t they? Well, yes they are, but many other insects are attracted to light and can be seen in and around light-traps. Here is some information on these ‘other’ insects, originally compiled for a BENHS workshop in December 2017.

Which insects are attracted to light?

The insect groups I have recorded at light-traps most often

From my own light-trap records over the last 20 years or so I was amazed to find that I had recorded 615 different species of insects other than moths. The most species-rich order for me has been flies, Diptera (especially craneflies), followed by Coleoptera, beetles (especially dung beetles, ladybirds and burying beetles). Caddisflies and lacewings are also strongly represented, but the total list includes a surpisingly large range of species from many different groups.

Here is my full species list (PDF). The final page of this list includes a comparison with lists kept by Andy Musgrove from near Norfolk – his top 20 species have quite a lot of overlap with mine, but also some species near the top of his list that I’ve never seen and vice-versa. The full list of species that could potentially be found in light-traps across the country must be very long indeed.

(Alternatively, download the full species list in spreadsheet format.)

Recording light-trapped insects

Many of the non-moth insect groups that are strongly attracted to light are covered by active recording schemes, that would be delighted to receive records from moth-trappers of these light-trap ‘extras’. One way of sending records in to most of the relevant schemes is to use iRecord, which allows you to add records for many different species groups and make them available to the various recording schemes (and local records centres).

Download a list of the ID resources and recording scheme links (PDF – updated on 11/12/2017) for the main groups of light-trapped insects. This document includes lots of links to identification resources for the different groups, many of which are available online.

Identification tips

If you’re on Facebook you should join the Moth Trap Intruders group – you can add photos there and get help with identifications. iSpot is another useful place for ID help across all species groups.

Here are the guides prepared for the BENHS workshop – these pick out a few of the species that you are likely to encounter and that can be identified fairly straightforwardly.

The mayfly Ephemeroptera lineata is one of the rarest species I’ve recorded in light-traps. It is mostly confined to parts of the rivers Thames and Wye. It comes to light in large numbers, much more so that the other two species in the same genus, which in my experience are not attracted to light.

Rothamsted light trap research

Here are three of the research papers that analyse non-moth records from the Rothamsted light-traps (sadly the two 1930s papers are not open-acess; the more recent one on the true bugs is open).

Thanks to:
  • Malcolm Storey (BioImages), Janet Graham, Donald Hobern, Martin Cooper and other photographers
  • Gary Hedges of the Tanyptera Project at Liverpool Museum (who passed on materials from a similar workshop earlier in the year)
  • Andy Musgrove for providing a comparison list from his light-trap catches
  • Marc Taylor, Ian Sims and Jon Cole of BENHS for organising the workshop

Details of future training courses from me are available here.

Details of future events and workshops from BENHS are available here.