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.

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.

A cool harvestman

Today I came across an unmistakable harvestman species, Dicranopalpus ramosus. This species has - or is in the process of - colonising Europe from its original home in North Africa. It is unclear if this expansion has or not anything to do with human transportation, but it has been suggested that it could could have been introduced with garden plants or horticultural produce, and the species has carried on expanding. It was first noted in the UK in 1957, and reported in Scotland in 2000.

 This is the second time I spot this harvestman. The first time (07/11/2009), was in the same location and also on a headstone (above). They have a typical resting posture, close to the substrate, with their long legs outstretched to the sides, and they often rest alongside leaves or branches this way. When resting on walls - or in this case on headstones - they are easy to spot. The second distinctive feature is that, their palps are forked. Males have a dark mask across the eyes and plain bodies about 4 mm in length, females have pale eye region and dark patterns in their body, palps and legs. 

Adults are found from the end of July onwards, peaking in September, apparently happy to live until February or March if the frosts don't kill them. 

A female

Male showing the usual stretched posture.

Close up of the same male.

No records were available for East Yorkshire, so these now have been uploaded into iRecord.

More information
Page in the British Spiders site.

Daddy superlong legs

Today's post celebrates harvestman season. This one, a male Leiobunum rotundum, sat on an outside wall, all outstretched legs. With an enormous leg span, well over 10 cm, it is amongst the longest legged harvestman in the UK. The species can be recognised by its dark mask around the eyes and contrasting black legs. Males have a rounded orange body, while females are brown-grey with a broad dark stripe along her back. The next photo gives you a idea of the relative size of the legs in proportion to the body.

Communal daddy long legs

These three daddy long legs (Opiliones), Paroligolophus agrestis, had found a cosy spot at the top of this apple. I am not aware that this species is particularly gregarious, although many daddy long legs do not dislike each others company and some actually form dense aggregations. The function of the social behaviour of daddy long legs is poorly understood and the explanations range from thermoregulation to defence. Although most individuals aggregating are adults, mating does not seem to explain this behaviour. The following video shows an instance of mass aggregation in Daddy long legs:

Harvestmen season

I have seen quite a number of harvestmen - also known as daddy long legs - in the last couple of weeks, and realised I hadn't posted on them yet. At a distance harvestmen look like skinny, long-legged spiders, but a close-up look reveals they are not spiders (see above a female possibly of Opilio canestrini). Harvestmen belong to the order Opiliones, within the class Arachnida, and they are related to mites, spiders and scorpions and so they have eight legs. They can be distinguished by their fused body, as opposed to the cephalothorax and abdomen of spiders, and more similar in looks to that of scorpions -but without the tail. They have two eyes close together on top of their body, on a tubercle, unlike spiders which have eight eyes. Their legs are very long, and the first pair is even thinner and longer and acts like antennae, constantly sensing the ground like a blindman's stick. They also have a pair of pedipalps and chelicers. Unlike spiders, harvestmen produce no silk, have no venom and are generalist feeders. They have two forms of defence: if trapped they emit a foul-smelling substance which acts as a deterrent to predators. They also shed their legs easily and the severed leg carries on moving for a while, which allows them to scape while the potential predator is distracted with the moving leg. One of the harvestmen I saw yesterday (below, possibly female Phalangium opilio) had only one leg on one side of the body: it wasn't the most elegant walker, but it managed to move quickly enough.

Another important difference from spiders is that harvestmen actually copulate, as males have an intromitent organ. This drawing, from Hillyard and Sankeys' monograph, shows the larger female and the male facing each other 'in copula'.

More information
Harvestmen: keys and notes for the identification of the species.1974 By P. D. Hillyard, John H. P. Sankey. Here.