Newborn Pholcus spider

A female Pholcus phalangiodes carrying eggs has been in the outside toilet for over two weeks. Today, I noticed her shuffling a bit, and when I looked, the first spiderling had been born and was sitting on the eggs. The spiderlings' folded legs and rows of eyes are clearly visible through the egg shells. When I returned five hours later, the female was holding a fuzzy ball of baby spiderlings.

For more on Pholcus on BugBlog click here.

Male harvestman

The adult male harvestman Phalangium opilio is one of the easiest to identify due to its enlarged chelicerae and white underside. Despite their large chelicerae, they are harmless as they have no venom glands. Males appear to use their chelicerae to fight. This individual settled quite well on the white bowl, stopping to groom its long, thread-like 2nd legs. Harvestman often use these legs, the longest pair, as insects use their antennae, tapping objects with them to feel their way around, as an organ of touch. 

Grooming its 2nd leg using the palps.

A whole view of the individual, showing their longer second pair of legs, the blurry one was on the move.

Fresh Painted ladies

It has been almost four years that I haven't seen a Painted Lady, but today I had a nice surprise when I spotted one, high on the buddleia, amongst the dozen or so Peacocks that are so abundant these days. Painted Ladies are warmth-loving butterflies, unable to survive our winters, so before the cold sets in, they will migrate to the Mediterranean. This generation is the offspring of the butterflies that migrated to the UK in the spring, from southern countries, as far as Morocco. They arrived, mated, laid eggs, and the caterpillars fed on thistles, with the new generation being the fresh painted Ladies that will migrate south. Painted Ladies have mass migration years, in which they are much more numerous than usual, and these years appear to coincide with warm summers when Hummingbird Hawkmoths and Silver Y moths also migrate in large numbers to the UK. The last mass migration year was in 2009.
 If you see Painted Ladies, you can contribute to the research into their migrations reporting your sighting to Butterfly Conservation Migrant Watch Survey.
  See previous posts on Painted Ladies in BugBlog.

The intricate patterns of the underwing of Painted Lady

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Looooong legs!

 This Dicranopalpus ramosus harvestman posed in the flattened, all legs stretched posture typical of the species. There were lots of them sitting on headstones in my local cemetery today. When disturbed, they walk as a 'normal' harvestman', but soon after sit and stretch their legs again.

A close up of the individual above, a female.

Legs for laying eggs

Most Nymphalid butterflies, a group of large species that include the Peacock, Painted Lady, Comma and the Monarch, have modified forelegs, smaller than the rest of the legs and normally tucked in under the head. In the Peacock (above) the forelegs are relatively large, but not used for walking and they even have the same dark colour as the body, giving the impression that the butterfly has only four legs. Why is this? Despite their vestigial appearance, experiments have shown that the forelegs have a very important function, especially in females. In the investigated Nymphalid species (mainly the Monarch and the Queen butterfly), the tips of the reduced forelegs in females - but not males - have sensory organs associated to spines, which they use to recognise specific chemicals from the larval foodplant when ovipositing. They drum the leaves with their forelegs, puncturing the leaves and releasing plant chemicals allowing their receptors to detect them (what is known as contact chemorreception). The antennae and the tips of the other legs also contribute to selecting the foodplant, with tapping with the antennae and drumming with the mid legs also observed when selecting foodplant. The forelegs are part of a very complex sensory system, possibly providing a 'backup' with the sensory spines protected from damage, by the forelegs being reduced and not being used for walking. Butterflies can be very selective in choosing foodplants, as they not only have to determine the species of plant, but also how healthy or how old the leaves are, so it is not surprising that they use a complex sensory system to assess this, which we are only beginning to understand.

This video from Arkive, shows a female Peacock tapping a nettle leaf with its forelegs while laying eggs.



More information

Baur, R., Haribal, M., Renwich, J. A. A. and Staedler, E. (1998). Contact chemoreception related to host selection and oviposition behaviour in the monarch butterfly, Danaus plexippus Physiological Entomology, 23, 7-19 DOI: 10.1046/j.1365-3032.1998.2310007.x

Myers, Judith. 1969 Distribution of foodplant chemoreceptors on the female Florida queen butterfly, Danaus gilippus berenice (Nymphalidae)." J. Lepid. Soc 23: 196-198.