Wednesday, 25 July 2012

Bees by behaviour

Summer finally arrived a dew days ago, and the bees have been enjoying the sunshine and warmth. I have been busy beewatching. It struck me that although there are hundreds of birdwatching books available, 'Beewatching' is not a shelf you will find in your trip to the library: number of beewatching books: nil, zilch, zero (sorry, no, I do not mean beekeeping). But why? Although bee watching has challenges, it is immensely rewarding. Plus points: (1) you can do it from the comfort of your garden, in fact gardens are amongst the best habitats to observe bees, as many flowers are available and you can pop out when weather conditions are optimal, therefore, no transportation needed (2) no binoculars or telescopes are necessary, and, (3) with a little investment on garden plants or a home-made bee hotel, you can be rewarded by new species coming to you and behaving as they do in the wild and even breeding in your garden: even small urban gardens can attract a large number of species. Given the lack of field guides on the topic, beewatchers are forced to made themselves out of experience, plenty of patience and readiness to learn. Although many bee species can only be identified under the microscope, some common garden species are relatively easy to identify while they are going about their business. I hope to show here that you can narrow down the group of bee or even identify to species level solitary bee species just by watching the various activities they are engaged with. 

Watch the flower
Many bees prefer to visit particular flowers. Some bee species are oligolectic, which means that they gather their pollen from one or a few flower species, others called polylectic, collect pollen from a wide variety of flowers. But even if the bees are polylectic, they often show some degree of preferences, therefore noting which the flowers they are visiting makes it easier to identify bees. This works even for males when they are patrolling and not feeding, as the males will check out the flower species that the females visit for nectar or pollen. A male Anthophora furcata, today, checked first one patch of Stachys sylvatica, then Lamium maculatum, then the other Stachys sylvatica patch. Surely, a female appeared later (below) to collect pollen in S. sylvatica, and the orange pollen she was carrying was probably from Lamium.

 Wool Carder Bee females are likely to be spotted shaving Lamb's ears (Stachys byzantina) hairs or feeding on the flowers. Megachile willughbiella loves cranesbills, campanulas and everlasting peas. Anthophora plumipes is strongly attracted to Lungwort and Comfrey. It also works the other way round: some plants are visited only by a reduced number of species: only a handful of garden species will visit foxgloves or honeysuckle.

Pay attention to detail
A large male bee patrolling campanulas is probably a leafcutter bee, Megachile willughbiella. To make sure, follow him as he flies, as he will settle regularly in a sunny, exposed place after bouts of patrolling (below).
Watch him carefully when he stops, he will almost invariably groom his head with his front legs a couple of times after landing - why? maybe wiping his eyes clean? -, and his white 'boxing gloves' will be visible even from a couple of meters away. If you can get closer, crouch down and look at him straight in the eye: he is all concentration, watching for females, rapidly twitching his head looking left, right or up. He does this for a few seconds and then flies off to carry on patrolling.

Leaf designing
A little bee flying from leaf to leaf, settles and walks sideways along the edge of the leaf briefly, like she is checking it, flies to the next leaf and then starts cutting an oval shape piece with her jaws.
Just finishing cutting the piece. Note that the same leaf has two other cut pieces.
In this shot you can see how she is holding the rolled piece of leaf with her legs and jaws

The edge of most leaves of my Enchanter's Nightshade plants, are all cut out. The culprit is the aptly named leaf-cutter bee, Megachile centuncularis. Leaf cutter bee females collect hundreds of leaf fragments to line their nests. As she cuts a fragment, she rolls it under her body using her legs and when she is finished she also holds it with her jaws before she flies up and then straight to her nest. If you can check the underside of her abdomen as she cuts the leaf, you will see the golden brush that characterises this particular species.

Spot the bully
I watched the first Wool Carder Bees of the year a couple of days ago in the local wildlife garden. Two males patrolling and feeding in a patch of Betony.
These are large, powerfully built bees, armed with five sharp prongs at the end of their abdomen. Males are territorial and they will readily attack and expel from their territory any other bees - even big bumblebees -, monopolizing the females that come to feed at their patch. When they rest, they keep their wings open at an angle, with their abdomen exposed. One of the males attacked a Bombus pascuorum feeding on the betony, and the bumblebee swiftly flew away.

Bottoms up!
Watch how the bee feeds on a flower. Leaf cutters (Megachile species) carry their abdomen tilted up, especially females, and rotate on the flower collecting pollen (see top shot). Look under their abdomen, you will see a broad brush of hairs. The color of the brush can help identify the species. They collect pollen on their rear legs and transfer it to the brush as they move over the flower. Megachille willughbiella females have a red and black brush, while M. centuncularis have an all golden one. Note that the hair color can be obscured by the pollen! This little video I took earlier today shows how she collects pollen on knapweed, a current favourite plant for bees in the garden.

Don't forget the little ones
Many bee species are small, you might have taken them for small flies in the past, but now that you are watching flowers up close you start to notice them. These two photos show flower preferences in two small Osmia specieswhich I only found in the garden this year. How could I have missed them before? 
Osmia caerulescens, the Blue Mason Bee, likes labiates like French Lavender, Sage or hedge Wouldwort
Osmia leaiana loves Knapweeds
Watch the seasons
Solitary Bees fly during relatively narrow periods, maybe two or three months in the species that have a single generation per year, so the time of year is often informative. Anthophora plumipes flies from March to early June, whereas Anthophora furcata has a short flying season in June and July.

There is so much to learn
As you become a beewatcher, you will develop a thirst for learning about the lives of these little critters that share your garden. For some of the species there is little information available, even common species have structures or behaviours that still remain enigmatic (what is the purpose of Megachile willugbiella boxing gloves or Anthophora plumipes hairy legs? why are the scopas of bees different colours, do they provide information to other bees, maybe when mating?). There are some resouces that I treasure, like my Bees of Surrey book by David Baldcock, or the BWARS site, and various bee identification forums, but as these are mainly concerned by identification and recording, I still want a beewatchers field guide.

Monday, 23 July 2012

Some day-flying moths

Following on the last post on moths, not all moths are nocturnal. Even if you don't want to go out there in the night looking for moths, you can come across many species of moth by day. There are over a hundred species of day-flying moth in the UK. Some species don't seem to care if it is day or night. Many day- flying moths are quite spectacular and often taken for butterflies. The following is is just a small selection of garden day flying moths.
 On the top shot, the Six spot Burnet, Zygaena filipendulae, on Betony, Stachys officinalis.
Silver Y, Autographa gamma, a strong migrant, it is often active during the day.
Mint Moth, Pyrausta aurata. The caterpillars of this small beauty feed on plants of the mint family.
The spectacular Hummingbird HawkmothMacroglossum stellatarum feeding on Red Valerian
Small Magpie, Eurrhypara hortulata. Flies by day in June and July.
Cinnabar Moth, Tyria jacobaeae. In flight, it is often taken by a pink butterfly.

Moth bat detectors and the evolution of butterflies

ResearchBlogging.orgThis noctuid moth, a male Large Yellow UnderwingNoctua pronuba entered the house a couple of nights ago and my cat alerted me to it. This is a large moth, very variable in colour: females are lighter than males, and both sexes have a black mark near the end of the wing. As most moths, they have a highly developed sense of hearing and can hear ultrasounds by means of a timpanal ear behind their middle legs, in order to detect and avoid echolocating bats. When they detect an incoming bat, moths carry out unpredictable flight maneuvers: suddenly flying up, carrying our loops or power diving or dropping with closed wings. Large Yellow Underwings also suddenly drop to the ground when they are flushed during the day. Their coloration is cryptic and they blend well with the leaf litter, so once they fall to the ground they are hard to spot.
Avoidance of echolocating bats is thought to have been the selective pressure underlying the repeated evolution of bat detecting tympanal ears in moths. This happened repeatedly involving different anatomical regions in various moth families more than 50 million years ago. Surprisingly, the evolution of diurnal butterflies from their nocturnal moth ancestors appeared to have occurred at the same time: day flying and the subsequent radiation of butterflies resulted from a bat avoiding strategy.

More information
Yack JE, & Fullard JH (2000). Ultrasonic hearing in nocturnal butterflies. Nature, 403 (6767), 265-6 PMID: 10659835

Friday, 20 July 2012

Chewing me timbers!

From June to October, I find Ectemnius digger wasps in the garden. They are formidable hoverfly hunters and, close up, they look so fierce: all enormous, forward facing eyes and long, sharp jaws. Females bore nests in soft, dead wood using their jaws: a central burrow with lateral cells which they stock with flies. They will lay eggs on the flies and leave their nests for their larvae to feed on the flies when they hatch. They use dead branches on trees, laying wood and even visit bee hotels. Males are often found inspecting holes in dead wood, in search of emerging females.
Year after year, these wasps come back to my log pile under the barbecue. A few days back, I watched a female searching for suitable nest sites amongst the logs. She settled at the end of a lime log and started chewing the wood, producing abundant sawdust in the process (top photo). She carried on for a while, although at the end I think she settled for a different log, as today a large pile of sawdust had accumulated underneath (below).
For more posts on Ectemnius digger wasps click here.

Monday, 9 July 2012

A beautiful wasp-mimic hoverfly

While in the wildlife garden a couple of days ago, I noticed a large boldly marked hoverfly male hovering by the pond. I managed just a couple of shots, but this one is enough to identify it as Chrysotoxum festivum, a relatively scarce hoverfly in the north of England. Unlike other hoverflies, this genus has long, forward-pointing antennae, which contribute to liken it to a wasp. There is little information on the biology of this genus, although the larvae have been found inside ants nests, where they presumably feed on ant-attended ground aphids. 

Sunday, 8 July 2012

Perching male Large Skipper

 Skippers are amongst my favourite butterflies. They are inquisitive, fast fliers, and males like to perch prominently in their territory, and then allow close approximation. I took a zoomed shot of this male with the macro option, which effectively blurred the background, and shows off the details of the butterfly, including the dark sex brand on the forewings. The following shot, in contrast, captures its surrounding environment, and illustrates how the tall Red Clover allows the male to obtain a broad view of the little meadow in a local wildlife garden where it lives, and to quickly spot and chase rival males. Golden skippers rest with the forewings held well above the hindwings at an angle, instead of resting the forewings over the edge of the hindwings, both on the same plane as in other butterflies. The meadow, with tall grasses, and dotted with Birds Foot trefoil, red clover and geraniums, is a typical habitat for this species.

Saturday, 7 July 2012

Dancing damselflies

I popped into my local wildlife garden in the middle of the day taking advantage of the sunny, warm weather. The pond was busy with Azure Damselflies, Coenagrion puella, at least two males and a female. A pair adopted the mating position, with the male holding the female by the neck, and her curving her abdomen forward (above). Another male flew close to check them out, below. The pair then moved onto the water, where the female laid eggs well under the water, still being held by the male. As I don't have a proper pond, I don't get to see damselflies very often, so it was nice to watch these in action.
 Mating pair and watching second male
A resting male Azure Damselfly

Zebra-striped hoverfly

It is unfortunate that not many hoverflies have English names - only the Marmalade Hoverfly and the Large Narcissus Fly come to mind. However, this large hoverfly, Scaeva pyrastri, with its very distinctive bold black and white abdominal pattern and hairy eyes could be named the Zebra-striped hoverfly, as suggested by John Wall in BugGuides. It is a high summer hoverfly, I have only seen it in July and August, and is a regular immigrant from the continent, and comes here to breed. It can feed on both tubular, deep flowers, like Red Valerian, Verbena bonairensis, Agapanthus and Lavender and also on flat ones like Fennel. Today's was the first of the year.

Thursday, 5 July 2012

Fork-tailed Flower bees mating

Many people are familiar with the Hairy Footed Flower bee, Anthophora plumipes. These are amongst the earliest active in the year and are easy to recognise: females look like a small, black bumblebee and males are tawny. They are superfast flyers, with a characteristic high pitch buzz. If you like these bees, you will probably like their small summer time relative, the Fork-tailed Flower bee. This is a more slender bee, similar in size to a honeybee, chocolate brown and also with a long tongue. As usual in bees, males appear first, late May or early June. Males are very distinctive as they have a yellow face, and they make a similar high pitch noise to A. plumipes when they fly. After emergence, males find a patch of their favourite flowers and patrol it checking every flower spike, stopping to rest or feed occasionally. Females will appear a week or so later, and are all brown, with a reddish patch of short hairs and the end of the abdomen. They show a strong preference for the hedge Woundwort, Stachys sylvatica, which they use to collect pollen, although they also visit several other flowers including Lavender, Lambs Ears, Foxgloves, Comfrey, Herb Robert and Iris and also occasionally Buddleia. 
Male sunbathing
Male on a Hedge Woundwort spike, showing its long tongue
The female resting. Notice the reddish patch of hairs at the end of her abdomen
A couple of year ago I established a couple of patches of Hedge Woundwort in the garden. This native plant attracts long tongued bumblebees as Bombus pascuorum and hortorum. Anthophora furcata males appeared much later than usual, on the 23rd of June. Yesterday, in a warm sunny spell between showers, I watched the male patrolling the Hedge Woundwort patch. A little while later, the first female appeared. Within seconds the male jumped on her, and both fell to the bottom of the flower bed, disappearing from sight for at least half a minute. Then the female emerged, climbed over the plants, flew and tried to feed, but the male jumped on her yet again. The top shot is the only shot I got from this mating attempt. Solitary bees often mate just once, shortly after emergence, so the days when males have emerged waiting for females might be the best chance to observe these rare events.

Belated National Insect Week celebrations

Insects couldn't really celebrate National Insect Week last week due to incessant rain or cloudy, cold weather. They came out today, a sunny, warm day and this gallery shows they did celebrate in the end. I spent some time trying to get a focused shot of a beautiful velvety male Eristalis intricarium, the first I have seen in the garden. He hovered at about 1 m of height over a patch of Red Valerian, swiftly chasing away any insect that invaded his airspace. The top shot is the best I got, by pre-focusing on a plant and then approaching the hovering fly. Not perfect but I was quite pleased with it.
A Silver Y moth, part of a local influx today.
A Merodon Equestris hoverfly covered in pollen.
The shiniest bluest bluebottle I have ever seen!
A soldier beetle on Feverfew in my local wildlife garden
Colletes bees on Oxeye Daisy
Bombus hortorum feeding on Linaria purpurea
A male Tree bumblebee Bombus hypnorum shows its colours
Bombus pascuorum feeding in Birds Foot Trefoil
One species that does not seem to be celebrating is the Wool Carder Bee, Anthidium manicatum. They didn't have a good year last year. Could they still be late? I do hope so.

Tuesday, 3 July 2012

Fearsome stripy jumper

Given the current rainy weather, I was pleasantly surprised to find this male Zebra Spider, Salticus scenicus, on my conservatory wall, inside. Zebra spiders have a bare black body, with white scales and some brown scales on the abdomen. They are warmth-lovers, coming out of their hiding places on clear days, often on walls after they have been heated by the sun. Salticus males have huge chelicerae for their size (a tiny 5 mm!), and they can be seen moving their palps over their black chelicerae as they move about. The chelicerae are opened in a display to rival males, and, if the contest escalates both males will face each other and lock their opened chelicerae together in a sparring match, as shown on this video in Arkive featuring a fight:

ARKive video - Zebra spider - overview
A top view of the male Salticus scenicus
Another male showing more brown (photo 20/04/11). The angle allows to see the long fangs folded underneath. Relative to its size, I think they are longer than in Dysdera.
 Despite their tiny size, Salticus make fearsome hunters. A few years back I surprised this male with a fly larger than him.
Male Salticus scenicus with fly (13/05/2009)
Female on 30/04/2011
Do you recognise this female? She is featured in the Bugblog banner. You can see her smaller chelicerae and white palps. Often females have beautifully marked black and white abdomens which give this spider its English name.

Monday, 2 July 2012

A close look at an Alder spittlebug

ResearchBlogging.orgThis cold Alder Spittlebug, Aphrophora alni, sat on a rose leaf, cold and reluctant to fly, so I decided to give it a session on the white bowl, and it graciously obliged. The Alder Spittlebug is one of the largest British froghoppers (9-10 mm), so called for their - alleged - resemblance to a frog and their ability to jump. Unlike the Common Froghopper, which is smaller and on close inspection covered on fine hairs, the Alder Spittlebug has fine dark punctures and is less variable in colour. They also have a distinctive keel in the middle of the thorax, visible in the photo below. They are sap feeding insects, both nymphs and adults, and they feed on a range of plants. Adults are usually found in trees, but they descend to lower vegetation to lay eggs. 
 Froghoppers are the fastest jumping insects, outperforming fleas: they can jump up to 70 cm in the air, with an acceleration equivalent to 550 times gravity. Their hind legs - tucked underneath their wings in the photos - are powered by huge muscles in the thorax and the catapult-like jump is effected by elastic energy stored in a membrane. Another fascinating aspect of their behaviour is sound communication. Froghoppers and other small homoptera have a repertoire of vibrational drumming sounds - inaudible for us - which transmit through the substrate where they sit and that individuals use in communication. Songs can be territorial, regulating the distance between feeding individuals, or involved in attracting a mate, emitted by males and to which females respond, and they also sing as a form of fighting when two males are close together or when in distress.
More information
Burrows M (2009). Jumping performance of planthoppers (Hemiptera, Issidae). The Journal of experimental biology, 212 (17), 2844-55 PMID: 19684220 Tishechkin (2003). 

Tishechkin, D.Y. (2003). Vibrational communication in Cercopoidea and Fulgoroidea (Homoptera: Cicadina) with notes on classification of higher taxa Russian Entomology, 12, 129-181

Sunday, 1 July 2012

Inside curly cherry leaves with their food

Yesterday we gave our cherry tree a light trim, removing shoot tips damaged by the black cherry aphid. The leaves curl up, sheltering hundreds of aphids (above). Inside the leaves, with their prey, there were hundreds of Harlequin larvae larvae, a few 2 spot larvae and with few adults of both species, a 10 spot ladybird and a few predatory hemipteran bugs.
A mirid bug Deraeocoris ruber (I think!)

10 spot ladybird, near a black cherry aphid

Fully grown Harlequin larvae

2 spot ladybird larvae

Two spot ladybird
An unusual 2 spot ladybird with 3 spots!