Harvestman arrives to the summer

I CAME across the first harvestman of the summer the other day, skimming over the leaves and stones in my rockery.

I presume they’re called harvestmen because you seldom see them until the summer is well-advanced. They’re often mistaken for spiders, and they are related to them, but there are some key differences. The most obvious one is their eight incredibly long and thin legs. Rather confusingly, the Americans tend to call them daddy-long-legs, a name we use for crane flies.

Another difference is that spiders have segmented bodies while harvestmen have the head, thorax, and abdomen fused into one blob. Spiders have eight eyes and harvestmen only have two, they also can’t spin webs and have no fangs or venom. They use their speed and agility to catch prey with hooks on the end of those legs.

They can shed the legs as a defence mechanism but losing even one can be a bit drastic, because as well as providing them with mobility and a method of catching prey, they carry a variety of sense organs — in effect they are their noses, ears, tongues, and possibly supplementary eyes.

They prey on small spiders, insects, slugs, and worms but also eat decaying plant and animal matter, fungi, and bird droppings. I came across someone on the internet who keeps them in a terrarium and feeds them on tiny scraps of bread, butter, and fatty meat.

They have been well-researched in this country and 17 species have been recorded. The results of recent field surveys are available on the website of the National Biodiversity Centre.

One odd piece of behaviour is their habit, from time to time, of clustering together in large numbers with their legs linked. The reason for this isn’t fully understood but it’s believed to be a ‘safety in numbers’ strategy. Certainly a lot of things, particularly birds, like to eat harvestmen. Another defensive strategy employed by many species is the ability to emit a strong and foul smell if they’re attacked. They are particularly vulnerable when they’re moulting, which happens about every 10 days and, because of those very long legs, can take 20 minutes to half an hour.