Monday, 21 October 2013

Cat flea

While grooming my cat, I noticed something in her hair, and I thought it was a little scab. It turned out it was a cat flea, Ctenocephalides felis. I held it between my fingers and thought how I would photograph it (live) without it jumping away. Fortunately, I found a little transparent plastic box which is part of the kids toys and put the flea on a white plate, and the box on top. The flea was very comfortable in this very narrow space, although it kicked its legs vigorously. I removed the clump of cat hair I had got it with and, voilà!  the flea was ready to photograph.
Cat flea photographic set up
Cat fleas actually infest a range of mammals, including dogs, racoons, sheep and many others. The adults live amongst the fur, feeding on blood. The eggs fall out of the cat and, those dropping on the animal usual sleeping places tend to be the ones developing successfully, and they are warmer and have the right humidity, as the larvae are very sensitive to cold temperatures and dry conditions. As for their food, they eat flea droppings, which are protein rich and contain only partially digested blood, so you could see this as a form of parental care, the parents providing food for the developing larvae in the form of droppings, which accumulate where the cat sleeps. 

More information
Rust, M. K., & Dryden, M. W. (1997). The biology, ecology, and management of the cat flea. Annual review of entomology, 42(1), 451-473. here.

Monday, 16 September 2013

Do adult female house spiders roam?

As you gather from my last post, it is quite common to come across adult male house spiders, Tegenaria, roaming in search for females in late summer and autumn. Females are supposed to wait for them at the bottom of their web funnels. I was puzzled to find this fully grown, beautiful female inspecting my cat scratching post, in the open, an hour ago. Do females roam too?

Sunday, 15 September 2013

Spider portraiture

It is quite flattering that several people have congratulated me over the years on the invertebrate photos I feature in BugBlog, thank you guys! I don't claim to be a photographer, but I am happy to share a few tips on the white bowl technique, which I regularly use on critters found around the house and garden, especially on non-flying ones. As today I found the first male house spider, Tegenaria sp., of the season, I thought a post on this topic was timely.
Before my daughter finished saying 'spider!' I got the little beast running across the kitchen floor into a little plastic pot. For this, I save any little plastic pot I come across. You know the onion salad pot from an indian takeaway? ideal! To hold the bug for a few minutes the pot does not even need to have holes on the top. I also have a 'proper' bug viewing pot (like the one featured in the photos below). My bug pots are always available on the side of the kitchen and I always carry one in my bag.
The second piece of equipment is the bowl. A flat-bottomed white bowl, like those used for soup, is ideal, as its sides help reflect the light. Better if there is a smooth transition from the bottom to the sides, as it will reduce undesirable reflections.
 I take the bug pot and bowl to the conservatory (or outside, weather permitting), as I like as much natural light as possible.
And push the cat out of the chair (sorry!).
 Then I remove the lid of the bug pot, put the bowl on top, turn it round to transfer the spider to the bowl surface.
I'd like to say that, although it is a common technique, I don't like to use the fridge to cool down the animal, I am impatient and I want to get the photos and release the animal as soon as possible. Many of the bugs are naturally slow and settle quickly on the pot, or stop long enough for the shots. Male spiders at this time of the year are challenging, as they are very jittery and require a bit of attention until they are posing well. Usually, tapping on the table will startle them and they will stop running around. Unfortunately, they often stop leaning on the side of the pot, so when you remove it, they are settled in awkwardly like so...
...which is not ideal. I move the pot slowly until the spider is in the middle and blow softly under the pot, until the spider spread its legs.
Now lets go to camera settings. I don't own a DSLR, just a bridge camera (Canon Powershot G12, if you are wondering), but you can achieve a similar effect with any portable camera. I first set the flash on, and increase the flash setting to +2, this is important if the bug is dark, as the auto flash setting will result on an overall dark animal and not a very white background. You might need to experiment with your camera to find the best flash setting.
No flash
Flash on to +1
Then I set the focal point to the top left hand side of the visual field (nearer to the flash itself), instead of the central position. This ensures the animal is not in the shade of the objective. If I didn't do this, once I cropped the photo, the bottom right corner would be grey, not white, as it would be shaded by the objective. You can simulate this on a cameral without this setting by focusing in the middle point and then moving the camera trying not to lose the focus so that the animal is located in the top left hand side of the visual field.
 Today, I experimented by holding the camera vertical, so that the flash light came exactly in front of the spider.
Set the camera to macro, and fire away. I usually take lots of photos, as I want to get the focus right on the animal's eyes and I try also several angles, which are often useful for ID purposes.
  I download the photos in the computer and do some basic processing. Crop the white/grey space out, adjust the levels so that the white background is actually white, remove specks of dust or dirt and sharpen a little. That's it!
White level adjustment
 This one is my favourite of the session today. Although the white background is not perfect, as it is greyer on the right hand side, I like the spooky effect of the spider leg shadows.

Monday, 9 September 2013

Wandering Lime Hawkmoth caterpillar

From mid August to mid September is prime time for squished Lime Hawkmoth caterpillars. Being ready to pupate, they leave the lime trees where they have fed all their lives in search of a suitable pupation site on the ground. As lime trees like streets and parks, I always find them crossing the paths, and most often than not, already squished by passers by. Keep an eye on them, they are as large as a pinky finger when fully grown, greenish to pinkish colour, and with a blue 'horn' at the rear end. We collected this one, which we found on the school grounds this afternoon, to watch the rest of its life cycle at home.

Sunday, 8 September 2013

The weird and wonderful Vapourer Moth

While having lunch, a bright, russet moth outside flew against the bay window glass again and again. After a while, I decided to capture it to check what it was. The moth was very unsettled, and carried on flying in the bug pot while we finished our meal. Shortly after, another similarly russet moth, a bit larger, flew against the glass and landed on a silky cocoon on the window frame. I went out and realised the reddish moths were in fact male vapoureurs attracted by a female on the cocoon. The second male was now mating with the female (above). The Vapourer, Orgyia antiqua is a very odd moth indeed. They have a striking sex dimorphism. Males have large, feathery antennae and often fly during the day. They are a rich russet colour with a white spot on each forewing. Females, in contrast, don't look much like moths, they cannot fly as their wings are vestigial, they have small antennae and enormous bulging bodies, full of eggs, and are pale grey in colour. Females will barely move in their short lives, attracting the males with pheromones they release shortly after emerging from her cocoon. The large feathery antennae of the males helps them locate the females quickly.
I took this photo from inside the house.
After mating for about 15 minutes, the male left (13:20). We could then had a closer look at the female. Eggs were visible through her thin abdominal skin. She looks velvety and heavy.
The female quickly started to lay eggs on the cocoon surface, the photo below taken at 15:15. Note that the caterpillar hairs, which are irritating, are embedded on the cocoon itself, so they may act as a defensive device for the eggs themselves.
After egg laying, female dies, so the adult stage is very short, about two days and they do not feed. The eggs overwinter and the caterpillars will be born the following spring.
  There are several British species of a few moth families showing this pattern of female flightlessness, amongst them the Winter Moth. The limited mobility of the females is compensated by the highly dispersive larvae, which might be able to balloon when little. In the UK adults are found from July to September.
On this photo you can see the vestigial wing: just a small hairy flap (the head is down and the abdominal tip up, egg laying).
At 16:41 she had pretty much finished laying.
 I searched around for more cocoons nearby and found one under a wooden shelf by a large cotoneaster, about 2 m away from the first one. It looked very fresh and translucent, and still contained a caterpillar.
The large oval cocoon and large caterpillar inside points to another female will emerge from this one too.

Saturday, 31 August 2013

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.

Friday, 16 August 2013

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

Sunday, 11 August 2013

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.

Saturday, 10 August 2013

Legs for laying eggs

ResearchBlogging.orgMost 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.

ARKive video - Peacock butterflies mating, laying eggs and caterpillars hatching

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.

Pied hoverfly

At the higth of summer, I occasionally see this stunning hoverfly, the easy to recognise Scaeva pyrastri. I am going to follow NatureSpot and others and use a common name, Pied Hoverfly, although swift hoverfly would be equally fitting to this migrant, quick flier. It is that time of the year when each flower in the garden is being visited by hoverflies, and the flowering fennel is attracting quite a few.

Thursday, 8 August 2013

Be quiet to get close to feeding Silver Ys

A still, balmy night, there are many Silver Y moths feeding on the garden flowers: lavender, perennial peas and buddleia. I always have trouble taking photos of the Silver Ys, they are so flighty! A step forward and they all disperse. A typical shot when I am outside is like the one above. My best shots have always been from behind the conservatory window. Today I understood why. If found out that you want to get close to these moths you need to be quiet. Why did this surprise me? I knew moths are able to hear bat ultrasounds and respond with erratic flight and even dropping to the ground, I even wrote a post about it. But there is nothing like first hand experience for learning. I tried to take shots from the cloud of silver Ys feeding in the buddleia tonight, they were visible in the dusk light as hovering silouettes by the profile of the large flowers. And then, as I approached, camera pointing up and triying to decide which one to shoot, I stepped on a crunchy leave inadvertently. The whole cloud of moths responded instantly by flying in different directions: of course they can hear! Many sounds we make while moving about are actually ultrasounds (click your fingers near a bat detector to test this). I bet walking on my pebbly path does this too, and this was what was keeping them away. I moved slowly, placing each foot carefully and slowly on the ground. Stood next to the buddleia and waited until the silver Ys came back and resumed their feeding. And this time managed some outdoor clear shots.

Catching the wind

The last couple of weeks have witnessed increased activity of garden ants. It is the season when winged ants (males and queens) take to the air forming swarms. Today I noticed groups of queens emerging from a nest in the garden. The queens climbed over the plants, warmed up their wing muscles and took to the air. They often land straight away unless they can get high enough and ride the breeze. This was that this winged ant was doing, with head and antennae outstretched, it checked if it was the right time to fly. The dark clouds in the background are also typical of flying ant days, as the prefer stormy, warm weather to emerge.
The lucky ones will mate in the air and come back to the ground, lose their wings and find a suitable site to start a nest. Many will perish though, eaten by birds or spiders.
 If you notice flying ants where you live, you can submit your record to the Flying Ant Survey, organised by the Society of Biology. It only needs a couple of minutes to fill the form.

Monday, 5 August 2013

Peacock eyes

I just like this shot from today, a Peacock nectaring on buddleia, beautifully showing its four eye spots.

Sunday, 4 August 2013

Nymphalid riot

The buddleias are now in full bloom in the garden, and buzzing with bumblebees, droneflies and butterflies. Today it was a particularly wonderful day for butterflies. Eight species were feeding, or passing by the garden, but the 5 Peacocks on one buddleia at the same time must have been a first. A Comma and a Small Tortoiseshell accompanied them at some point. A Speckled Wood fluttered by the garden, not settling long enough for a photo. The three common white species were about, some egg laying and a darting skipper - which didn't settle either made an appearance too.
 The Peacocks spend most of the time feeding on the buddleias, occasionally settling on the wall or the ground for a spot of sunbathing. The Small Tortoiseshell sat on top of the fence, allowing me to take a photo of it at an unusual angle.
A great day for a Big Butterfly Count too.
Peacock underside, such an amazing contrast between the brightly coloured upper wing colours.
Peacock and Small Tortoiseshell together

Two of the five Peacocks feeding on the buddleia
Large white
Small White
Sunbathing on the ground
Comma, showing the paler underside of the summer generation