Glow Worms

Look for them from late May to early September (with a peak in mid July), as soon as it gets dark. They glow for a few hours at a time, and usually stop glowing soon after mating. If you do see glow worms, don’t disturb them and certainly don’t take them home as trophies, no matter how many there are on a site. Their continued existence at your site could be on a knife-edge. But a short look by torchlight will do no harm, and you may see the smaller, darker (and virtually glow-less) male mating – perhaps even several on one female!

You may also spot larvae, particularly on dark, moonless nights. They glow much more faintly, and only intermittently, for a few seconds at a time. They are also not worm-like but have segmented bodies and six legs at the head end, quite similar to the adults. They do, however, sometimes help themselves along with their tails when moving, which makes them look a bit like caterpillars. You are more likely to see them on vegetation, searching for snails, than in the same areas as the glowing females. It is important for the survival of the glow worm to find the sites where the larvae live, since only about one per cent of its life is as an adult. Comparatively little is known about the preferred habitat of the larvae, so reports of them are always welcome. They appear over a longer time span than the adults, supposedly between April and October – probably whenever conditions are right for snails and slugs.

Surveys

If you would like to carry out a glow worm survey (particularly along the Tarka Trail), please print off survey sheets to take with you and then input the details using the form below.  Please include as much detail as possible.  We will collate these surveys and will use the information to update the Devon Biodiversity Records Centre (DBRC)

Threats include habitat destruction and fragmentation, pollution, distraction from artificial lights, insufficient grazing and climate change.  Further information

Name

Email address

Date of survey:

Time (24 hour clock):

Grid Reference (if known)

Description of site

Weather conditions

• Dry:
• Raining
• Wet ground (droplets on vegetation)
• Windy

Position of glow worms (click on all that apply)

• Short grass
• Long grass
• Under trees
• In hedge
• On path
• On gravel or stones
• Other

Light Pollution

• None:
• Distant lights: over 200m:
• Distant lights: over 50-200m:
• Bright lights nearby:
• House lights only:
• Lights from passing traffic:

Number of males (usually only seen with females)

Number of females (glowing)

Number of larvae (occasional glow)

Comments: Anything about the site (e.g. early records of glow worms not previously reported, changes in use of the site either in the past or planned).

Upload Photos