Monday, 20 May 2013
Sunday, 19 May 2013
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.
Thursday, 16 May 2013
Footballer hoverflies are commonly seen near water: ditches, ponds and drains, their genus name Helophilus, actually means 'lover of marshes' in Greek. On a little twig over a puddle on the pavement by a busy road, two Helophilus pendulus females - their abdomens large and turgid with eggs - laid. While one of them was busy actually laying under the twig, the other seemed to be 'feeling' the twig with the ovipositor, probably selecting the best site to lay her shiny white eggs. Note the ovipositor stretched out. Helophilus lay their eggs on clumps - like bluebottles - unlike other hoveflies which lay individual eggs singly. This might well be due to their different feeding habits. Many hoverfly larvae are predatory, and being born away from hungry siblings might give them a better chance to find food (like aphids). Helophilus are related to Droneflies, and their larvae, called rat-tailed maggots, are aquatic, and develop on very wet manure or submerged rotting organic material often in large numbers, so they are less likely to compete for food. Their 'tails' are actually long telescopic breathing tubes, that they can retract into their bodies.
For a great series of shots of Helophilus egg laying and larvae development check BugGuide.
Another shot of the laying female
I turned the twig to reveal the egg clutch after the female lad left. As they lay under the twig, the eggs are not readily visible.
Sunday, 12 May 2013
here for a scanning electron photograph of these openings. The fangs act as hypodermic needles, injecting the venom inside the prey's body. The teeth that help hold the prey while the venom is injected are visible at the bottom.
Pholcus phalangioides. Male on the right, not its elongated abdomen.