Spider eggs and egg sacs

Spiders make remarkable mothers. One of the most widespread maternal behaviours is the more or less elaborate construction of an egg sac, and many species are making them at this time of the year. The mother wraps a batch of eggs - which might be the only one she will produce during her lifetime - into a neat parcel kept together with silk. The egg sac can protect the eggs from parasitic wasps, or from predation - sometimes from other spiders. In addition, egg sacs are often guarded by the mother, like the Neriene montana above (28/05/2014) or Garden spiders (below), Araneus diadematus, which guard their large egg sacs until they die at the end of autumn (30/10/2011).

Holding the egg sac is another maternal behaviour. An example is Pholcus phalangioides, the splindly daddy long-leg spider. She makes a simple egg sac, with the eggs clearly visible through the lax packaging. She keeps the eggs on her mouthparts until the spiderlings hatch (22/07/2009).

Being mobile spiders, wolf spiders and nursery web spiders actually carry their egg sac with them wherever they go. This allows the eggs to develop faster, as they warm up when spiders bask in the sun.

Wolf spider, Pardosa sp. carrying her egg sac (31/05/2011), attached to her abdomen.

Nursery web spider carrying its large egg sac (19/06/2011).

In the family Gnaphosidae, the female not only guards the eggs, but she makes her egg sac inside a folded up leaf, locking herself inside with the eggs (19/07/2010):

But egg sacs are often found alone. Some of them have a stalk, like those of the genus Ero, also distinctive by their covering of coarse red silk (7/04/2013):

Others are truly unique, and is the best way to identify the species, like the sputnik-like egg sac of Paidiscura pallens, a tiny spider (28/05/2014).

Eggs vary in colour, I love the soft pink eggs of Steatoda bipunctata (28/05/2014)...

 ...and also the baby blue silk of Enoplognatha sp., revealed here while picking apples (30/08/2011):

These are just a few examples, from common spiders you can find in your own garden, which illustrate some of the diversity of spiders.

Vapourer caterpillars hatching

I have been keeping an eye on the Vapoureur egg clutches from last autumn every few days. watched a male being attracted by a female just emerged from her cocoon on the windowsill. They mated and the wingless female laid eggs on the cocoon itself. it is thought that the irritant hairs that the caterpillar weaves on the cocoon silk might offer protection to the eggs and young caterpillars.
It has been eight months and the eggs have overwintered and their development has speeded up as the days warmed. Today, in between showers I had a look and noticed nine open eggs and five tiny caterpillars indicating that probably some of them have already dispersed onto nearby plants.
The other egg clutch nearby is showing no signs of hatchlings as yet.

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.

Wolf spiders with egg sacs

Suring a sunny spell, the first wolf spider of the year carrying an egg sac - likely to be Pardosa amentata - run across the warm concrete in the garden. The silk on the egg sac was still bluish, indicating that it was very fresh. A little later I found another one sunbathing on the conservatory frame (below). A male kept approaching in full courting display mode, but she quickly lunged at him and retreated like saying 'go away, you are wasting your time'.
 Female wolf spiders as many other spiders display maternal behaviour. First, they carry their eggs wrapped in a silky egg sac until their spiderlings emerge. As these spiders move about in search of prey, this offers more protection to their eggs from casual predators than if the egg sac was attached somewhere and left on its own. Then, they open the sac when spiderligst are ready to hatch and allows them to climb on her back. The spiderlings will ride their mum for a few days before dispersing. These are sun-loving spiders, actively moving to and from sunny spots to adjust their temperature to higher than the ambient temperature in a similar way to lizards. Being carried about by their mother - both eggs and young - is likely to serve thermoregulation purposes, optimising the speed of egg and young development, as females of some Pardosa species have been shown to prefer higher temperatures than males and immatures.

Basking female.

Despite the mother's best efforts, wolf spider's egg sacs are often parasitized by tiny often flightless ant-looking wasps of the genus Gelis. Read this post by Chris Buddle to find out first hand about wolf spider egg parasites.

A Gelis wasp runs on the blue bin lid.

Click here for more wolf spider posts in BugBlog.

House spider with egg sac

Under the lid of the water butt in the garden I found this small Tegenaria, guarding its curious egg sac. I had never seen a Tegenaria egg sac before, the reason being that, according to W.S. Bristowe, their egg sacs are normally attached inside the spider's funnel, where they would be hard to see. In this case I probably broke the funnel when opening the lid and the egg sac seems to hang from the plastic by a few threads of silk. This peculiarity and its small size compared to other Tegenaria specimens make me think it is T. domestica, a species found in or outside houses. I hope I didn't disturb the spider too much, as I plan to follow the development of her spiderlings, which stay with their mums for a few molts inside her funnel.

UPDATE 9/06/2014. I now believe the egg sac belongs to a spider of the genus Ero. See this BugGuide thread for more info.

Larvae in a poo costume

Of all insect larvae I have come across, these have been the trickiest to spot. Red Lily Beetle adults were mating and laying eggs on my Asiatic lilies this afternoon. I was sitting next to the lilies and I was intent on spotting the larvae. It took a while. They look exactly like wet caterpillar poo. 

The bright orange eggs are laid in rows under the leaf, and when the larvae hatch they stay together and start eating the leaf where they have been born, their slimy droppings are deposited on their back, forming a faecal shield which grows in size with the larvae. The faecal shield disguises the larva, presumably helping to protect them from predators. When small, larvae fed on the underside of the leaf, leaving the upper leaf surface withered. As they grow they disperse from their siblings and they may move to the upper side of the leaf, eating the whole leaf or flowers as they grow. If they feel disturbed, they completely retreat inside their fecal shield, when they relax, their shiny black head and short legs are visible (above). The fully developed larvae drop to the soil where they make a white cocoon. There is a single generation a year, the new generation of beetles emerges and feeds before overwintering in the soil.

A string of lily beetle eggs

A cluster of young larvae - the leaf has been turned upside down to take the photo. The withered end of the leaf can be seen in the background

Neriene montana egg guarding

The contrasting red background of a kids wheelbarrow, made it easy to spot the egg sac of this Neriene montana female. The yellow eggs are visible through the loose, gauze-like silk wrapping of the egg sac. The female hangs upside down on her hammock web by the egg sac. She may possibly be able to lay more egg batches, as the female lives up to 7 months. Although egg guarding has not been reported in many money spiders and I could find very little on the reproductive behavior of this species, this photo confirms that the eggs may be laid very close to the web and will undoubtedly benefit from the female being nearby.

The very pregnant spider

 Most of the very abundant female wolf spiders in the garden (Pardosa sp.) are looking like the one above: their distended abdomen indicating they are about to lay eggs. I only saw one was already carrying an egg sac, the first of the year, sunbathing on the fence.

Lay them and eat them

During the past week, Harlequins have become more noticeable. I spotted a few walking on a tree trunk in my street. Today, passing by the same tree I had a look and saw many clusters of bright yellow-orange eggs laid on small crevices on the tree trunk, they are not wasting time! One of the Harlequins seemed to be laying (above). I also noticed that some egg clusters looked like they had been partially predated. The culprit is not hard to find: Harlequins are known by their cannibalistic tendencies, so - hungry after winter - , they may turn to eat eggs laid by other ladybirds. They also may be able to eat their own unfertilised eggs.

A Harlequin stretching its wings in the sun

A cluster of eggs

Harlequin near cluster with predated eggs

A close up of another cluster. Note the chewed up egg on the top right hand side.

Hoverflies to the rescue!

Despite being so early in the year, aphids are already covering the shoots of many plants. I saw my first Episyrphus balteatus of the year today. Basking on the warm, springy sun and then taking an interest in a small rose. I watched her while it flew away and back to the rose, chosing a fresh shoot and then adopting an egg-laying posture. I was surprised, but the camera was ready in my hands. The first one of the year and it was already mated! The hoverfly left and I looked at the rose stem.

 A bright white egg sat surrounded by fat aphids. What a well chosen place! Hopefully the aphid infestation will soon be under control thanks to the voracious hoverfly larvae.

Daddy long legs spiders

I like having spiders at home - yes, I know, it is a bit weird and they might scare the visits. A couple of years ago we had an enormous garden spider (Araneus diadematus) in our kitchen, next to the back garden door and it eventually attracted a male. We watched the whole courtship over breakfast - live - it was fascinating. The male was extremely careful and moved slowly. A few times there was contact between the pair's legs. Unfortunately the poor male must have taken the wrong step, as the female grabbed him, and unceremoniously rolled him in a broad band of silk band and ate him. From then on we called her 'The Cannibal' and released her outside a little afterwards for her to lay eggs. I am not sure that male managed to mate before being eaten. Living on a restricted diet indoors, the female probably saw him more like food than like mate. Anyway, don't let me get distracted, I was going to talk about Daddy long legs spiders, Pholcus phalangioides, to be precise, who had lately fascinated me. If you have an outside toilet or a room next to a garden, have a look at the corners of the ceiling. You can maybe see thin 'upside down' spiders with spindly legs.

These are the spiders I am talking about. They look a bit like harvestmen, but the fact that they hang from a web tells them easily apart. Well, the spiders have lived with us for a few years, the occasional one being swallowed by the hoover. The other day I noticed one with a large prey wrapped in silk. When the spider discarded the remains I had a look and it seemed to contain a large spider, most likely a Tegenaria. Now is the time of the year when male Tegenaria move around the house - often falling into baths - and maybe it is now when they are more likely to fall prey of patient Pholcus. This is another spider capture I photographed:

Then a few days later I noticed that a Pholcus living in the outside toilet had a sac of eggs. I pulled the camera out to take some photos and, after looking at them realised that the female carries the eggs in her mouth, but they are not wrapped in a cocoon like other spiders but are visible, probably held together with a little silk. Apparently the females live for several years and can protect the eggs themselves - and possibly the spiderlings - also, because the females move to a different spot every few days, it makes sense to carry the egg sac with her.

Of course, this makes the process of spiderling hatching from their eggs visible - and relatively easy to photograph - too, and there is when I found this incredible set of photos of Pholcus spiders being born at bugguide.netAnother very informative website with good photos:
http://www.xs4all.nl/~ednieuw/Spiders/Pholcidae/Pholcidae.htm