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Glow-worm numbers!!! please help |
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Paramesotriton
Member Joined: 16 Feb 2006 Location: United Kingdom Status: Offline Points: 3 |
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I've also seen some in Essex near Colchester, only adult females though. Sorry I've misunderstood your post I think Jon, are you measuring the pronotum of the larva to find sex ratios? |
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herpetologic2
Forum Coordinator Joined: 15 Jun 2004 Location: United Kingdom Status: Offline Points: 1511 |
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Yep
Jon |
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herpetologic2
Forum Coordinator Joined: 15 Jun 2004 Location: United Kingdom Status: Offline Points: 1511 |
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The larger the pronotum the most likely it will be a female - therefore you get the age class 1st, 2nd and 3rd years it seems a good spilt between the two sizes may relate to the sexes of the larva - hence sex ratio of capture animals I also collected around 15 larva and I reared them on in a tank - they laid eggs and I actually got quite a few eggs - and reared on the larva for release at the site wher ethey were collected.
Heres is a white larva - just hatched (above) placed on a penny Here is a normal coloured larva - placed on a 5pence piece
I have an account of all the larva captured but I havent got the info to hand - I will ge tthis together and show you the results
Regards
Jon
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Mick
Member Joined: 10 Jun 2005 Location: United Kingdom Status: Offline Points: 184 |
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Yeh, that 2nd pic's like the one i encountered at that BBONT reserve. At first glance i thought it kind've resembled a bigger, plainish Ladybird larva, but that's me!
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herpetologic2
Forum Coordinator Joined: 15 Jun 2004 Location: United Kingdom Status: Offline Points: 1511 |
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Here are some pronotum measurements from a population of glowworms in Berkshire. The 20 larva which measure over 3mm (width of pronotum) are more likely to be female while the 2mm are possibly males or larva in their second year - the 1 to 1.5mm are in their first year. These were all relocated from a works area last year into adjacent habitat - all larva were found under roofing felt tiles
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herpetologic2
Forum Coordinator Joined: 15 Jun 2004 Location: United Kingdom Status: Offline Points: 1511 |
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As shown in following picture |
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Vicar
Senior Member Joined: 02 Sep 2004 Location: United Kingdom Status: Offline Points: 1184 |
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Is this one Jon ? Didn't know what it was, so took a picture. Under a tin at Pirbright, Surrey last weekend. |
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herpetologic2
Forum Coordinator Joined: 15 Jun 2004 Location: United Kingdom Status: Offline Points: 1511 |
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Yep thats a glowworm larva alright
Jon |
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*SNAKE*
Senior Member Joined: 16 May 2004 Location: United Kingdom Status: Offline Points: 226 |
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Suzi
Senior Member Joined: 06 Apr 2005 Location: United Kingdom Status: Offline Points: 1025 |
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I have done summer surveys for glow worms for 10 years now. There are a few academics who study them and I forward my results to them and the RSPB who manage the heaths. They seem to have a few things in common with reptiles. Their requirements of habitat often match up with those of adders and lizards and like adders what would seem a good place in our eyes is not seen that way by glow worms. The other factor is once lost to an area they can only move back under their own steam - no flying or blowing on the wind. The males fly but not the larvae or females. They do have boom and bust years which again are hard to evaluate. The repercussions of weather and drought are not felt immediately due to the lifecycle of the glow worm so this also makes it hard. On one of the heaths I survey the distribution of the glow worms more or less exactly matches that of the adders found there. There is an excellent website on UK Glow worms and articles are included showing which councils are sympathetic to their plight. |
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Suz
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