11.005 Lichen Bagworm (Dahlica lichenella) case with pupa inside on a lichen covered dry stone wall at Stainland on Mar. 31st 2016. One of eight cases found in March and April that year over a kilometre stretch of wall.

April 9th 2016: After removing the cases from the dry stone wall I carefully glued them to some card back at home so they would be in the correct position for any emergences taking place.

 I was amazed just nine days later when the first adult bagworm emerged - but not the one I was expecting. It was the first confirmed record for Yorkshire of Lichen Bagworm (Dahlica lichenella) where only the wingless female is known in Britain. She is parthenogentic so she's all ready to lay eggs on emergence without the need for mating - she spent the next few hours doing just that.

After she had finished laying I opened up the case and was surprised to find eggs inserted all the way to the back. The eggs are surprisingly large due to the fact that they swell considerably after being laid. My next thoughts were how I would set about rearing them through and then hopefully release them back at the site were I'd found the cases. The colonies can be vulnerable due to minimal dispersal strategies.

Apr. 29th: twenty days later and the eggs have begun to colour up slightly and the eyes are now visible which makes them quite endearing.

May 4th: 25 days later and proof if proof were needed that the female is indeed parthenogenetic - the first egg begins to hatch. The eggs hatched in ones and twos over the following days and were reintroduced to the wild.

11.005 Lichen Bagworm (Dahlica lichenella) case on an lichen covered dry stone wall at Stainland on Mar. 31st 2016. I'm assuming it's another of this species because the case contained a rather plump parasitic wasp grub so I'll never know for sure.

11.005 Lichen Bagworm (Dahlica lichenella) case with a pupa inside on an lichen covered dry stone wall at Stainland on Apr. 14th 2016. The cases varied quite a bit in colour, this pied one stood out from the surrounding stone and was quite easy to find.

Eight days later and the case pictured above produced another female which went on to produce another large batch of eggs - around thirty here.

On my second visit to the site on Apr. 14th I was accompanied by Andy Cockroft who soon found the above case which produced this female. The abdomen of the freshly emerged moth is bloated with eggs allowing for the orange "expansion joints" to be visible. 

 The same moth as above around six hours later still egg-laying. The abdomen has now deflated allowing the dark abdominal plates to join together as one. The moths are about 2.8mm in length and appear black to the naked eye, hats off to anyone who finds these in the wild.

To separate this dahlica species from the other two likely candidates, examination of the pupal headcase is necessary. I've included a couple of photos below to illustrate what my identification is based on using the UK Moth website.

THE RESULTS: Of the nine cases found, including one last year, here's what they produced:
3 Adult females
2 Parasitic wasp grubs
1 Dead larva
1 Feeding larva
2 Full of lots of empty egg shells = breeding success earlier.

A return visit on Oct. 24th 2016 revealed many groups of up to 8 cases with an estimated population running well in to three figures. The cases were on both sides of the wall on both sides of the path.



Mar. 23rd 2014: Brian Leecy, Andy Cockroft (pictured) and myself went in search of the Dotted-margin Bagworm at Pecket Well clough, Hardcastle Crags. Brian had recorded them here both last year and earlier this year so our hopes were high. As the larvae inhabit the nooks and crannies around the roots above ground at this time of year a torch and kneeling mat is pretty much essential. 

11.001 Dotted-margin Bagworm (Diplodoma laichartingella), a case in a Beech tree hollow, Pecket Well clough, Mar. 23rd 2014. At last, after several years of searching I finally see my first bagworm case!!! 
At around 8-10mm in length and typically covered in dried insect remains and other detritus, the cases of this species are very difficult to find unless you know exactly what you're looking for.

Another shot of a case in situ showing no signs of life what's so ever. Very well done to Brian for finding them here in the first place!

11.001 Dotted-margin Bagworm larva and case. I took five cases home to rear through and unexpectedly all contained larvae. I'll try feeding them with mosses, lichens and even a dead insect or two.

When disturbed the larva picks up it's case and slowly wanders off. It seems to have everything on its case apart from the kitchen sink - there's even a caterpillar's head capsule and part of its thorax attached to it's rear end.

Eight cases were found that day, seven at Pecket Well and one in Middle Dean wood.

Just hanging around! It's Mar. 29th and 6 days since they were collected and no signs yet of any feeding activity. I presume they're still in diapause and haven't "woken up" yet. 

Apr. 21st: Well, none of the larvae showed any signs of feeding and appeared to have gone straight to pupation after a couple of days settling in period. The first adult emerged this morning resting patiently on its old case with the empty pupal case protruding to the left. It's a "well marked female" (Harry Beaumont) and is "calling" for males by extending her ovipositor from her rear end to release pheromones. Observing her through the camera's monitor I couldn't tell if it was the breeze from my open window making the tassel on the end waft around or whether it was she herself waving it around.

I've certainly never seen anything quite like it before!

Apr. 25th and another female has emerged and again she is "calling" in the same manner as the first. This time however those pheromones were soon going to be put to good use. 

Minutes later and I noticed another moth had also emerged but this time it wasn't calling and it most certainly wasn't staying still - it was a male! Friedrich states that males "usually become active within half an hour of emergence and fly continuously until they have completely ruined themselves". So after it had head-butted the ceiling a few dozen times I potted him up and introduced him to the female. No prizes for guessing what happened next.

Pair in cop.

After all the fun and games all that is left is a series of empty cases, each with a pupal exuvium protruding from the free end of the case.

 11.001 Dotted-margin Bagworm (Diplodoma laichartingella) found resting on a tree trunk at North Dean wood on June 17th 2020.


Colin D said...

Supeblyannotated Charlie great piece of work

charlie streets said...

Thanks Colin, because of the difficulty in finding them (in Calderdale) and their fascinating life cycles they are my favourite group of moths.

Bobolink said...

Staggering stuff. Well done and thanks for posting.