Termites on a trail

Termites (possibly Hospitalitermes sp), Doi Chiang Dao, Thailand
Termites (possibly Hospitalitermes sp.), Doi Chiang Dao, Thailand

I came across these termites moving along a water pipe on the Gully Trail at Wat Tham Pha Plong, Doi Chiang Dao, northern Thailand. The pipes provide water for the monks and their guests at the temple, but they also provide a convenient thoroughfare for the termites, helping them to move through the forest without having to traverse the ground!

Termites on water pipes, Gully trail, Doi Chiang Dao, Thailand
Termites on water pipes, Gully trail, Doi Chiang Dao, Thailand

These are nasutiform termites, which is to say that the soldiers have a pointed snout – a nasus – and are bit smaller than the workers. Presumably they make up for their lack of stature by being armed with a chemical spray gun, which can shoot a noxious aerosol of glue or repellent at any foe, particularly ants.

Termites (probably Hospitalitermes sp) nasute soldier outlined
Termites (probably Hospitalitermes sp.) nasute soldier outlined

There are at least 92 species of termite (Isoptera) in Thailand, including 7 genera in the subfamily Nasutitermitinae. (1) Most species in this subfamily are found in jungles and forests; they do not usually attack man-made structures, but rather feed on lichen, lichen-bark, dead leaves, branches, twigs, and other plant matter. (2)

I am not certain, but I think these are a species in the genus Hospitalitermes (Holmgren). There are six Hospitalitermes species in Thailand (1) and they forage openly during the day, as here. Other possibilities from northern Thailand are Nasutitermes, Bulbitermes, Aciculitermes and Havilanditermes. Lovely names!

Termites (probably Hospitalitermes sp.), large worker
Termites (probably Hospitalitermes sp.), large workers and slightly smaller, nasutiform soldiers

It is possible that the termites were heading out from their nest to forage in the jungle. I could only find one worker carrying a food-ball in the photos I took (below). Termites are of course decomposers; Nature’s way of cutting up and breaking down wood and vegetation. But they don’t do it alone; they need the help of microbes, symbiotic protozoa which they carry in their guts, to break down cellulose.

Termites (possibly Hospitalitermes sp.). One working (outlined) is carrying a food ball.
Termites (possibly Hospitalitermes sp.). One working (outlined) is carrying a food ball.

What termites lack in size they make up for in numbers. One study of termite abundance in Thailand, found that they were on average 6,450 individual termites per square metre, weighing about 10.7 g. If we scale up this termite biomass, which comprised many species, it gives a total weight of 10.7 million g or 10,700 kg per square kilometre. If I have got my arithmetic right, that is a fantastic ten tonnes per square km! The same as two or three large elephants!

Termites (probably Hospitalitermes sp.) walking along a water pipe
Termites (probably Hospitalitermes sp.) walking along a water pipe
  1. Sornnuwat, Y., Vongkaluang, C., & Takematsu, Y. (2004). A systematic key to termites of Thailand. Kasetsart J (Nat Sci), 38, 349-368.
  2. https://www.termiteweb.com/the-nasutitermitinae-termites/
  3. Inoue, T., Takematsu, Y., Hyodo, F., Sugimoto, A., Yamada, A., Klangkaew, C., … & Abe, T. (2001). The abundance and biomass of subterranean termites (Isoptera) in a dry evergreen forest of northeast Thailand. Sociobiology, 37(1), 41-52.

Stingless bees and resin bugs

Stingless bees (Trigona sp.) emerging from trumpet-shaped nest entrance below dipterocarp tree
Stingless bees (Trigona sp.) emerging from trumpet-shaped nest entrance below dipterocarp tree

The peculiar shape of this nest entrance caught my eye. Bees were moving in and out of the trumpet-shaped nest which was located below a large dipterocarp tree, at the foot of Doi Chiang Dao mountain, north of Chiang Mai, Thailand.

Stingless bees (Trigona sp.) emerging from trumpet-shaped nest entrance
Stingless bees (Trigona sp.) emerging from trumpet-shaped nest entrance

These waxy nests are constructed by stingless bees (Meliponini tribe of the family Apidae), a large group of eusocial insects – meaning they live together in colonies with a queen and have different castes – which play an important role in the pollination of crops and wild flowers in tropical countries. Thirty species of stingless bees in the genus Trigona, have been recorded in Thailand; T. collina is the most common species in the north of the country. (1)

Stingless bees (Trigona sp.) emerging from trumpet-shaped nest entrance
Stingless bees (Trigona sp.) emerging from trumpet-shaped nest entrance

As the name implies, stingless bees lack a functional sting, but they have powerful jaws and will aggressively defend their nests against intruders. Non-foraging bees near the nest entrance are there to protect the nest from a range of insects including parasites – which might try to enter. They also deposit fresh resin on the external entrance tubes, in order to deter ants, which are important predators of the bees. (2)

Stingless bees (Trigona sp.) at nest entrance
Stingless bees (Trigona sp.) at nest entrance

The nests of stingless bees are usually associated with a living tree, either in a cavity in the trunk or at the base of the tree, as in this case. The nest architecture is extremely variable between species, but the shape of the external nest entrance, as well as the internal nest features, are often characteristic of a given species. When nests come under attack, hovering bees emerge in force to defend the colony: they ‘face the nest entrance, and engage in aerial fights with non-nestmates, or directly attack larger animals, which retreat with a cloud of defending bees surrounding the head’ (2).

Stingless bees (Trigona sp.) at nest entrance
Stingless bees (Trigona sp.) at nest entrance

Based on looking at different photographs posted on the Internet, the trumpet-shaped nest opening looks like it might be that of Tetrigona binghami (Schwarz, 1937), also called Trigona apicalis variety binghami Schwarz 1937, although this species was only described for the first time in 2005, in Thailand. (1) Such an identification can only be tentative as there is no definitive key available online that I am aware of. The bee’s nest was located near the base of a huge dipterocarp tree, Dipterocarpus alatus, which was festooned with epiphytes.

Dipterocarpus alatus, Chiang Dao
Dipterocarpus alatus, Chiang Dao

Stingless bees live in colonies of somewhere between a few hundred to several thousand individuals. They usually visit many different types of flowers although some species seem to be fairly host specific. The main host plant of T. binghami is said to be teak (Tectona grandis), whereas T. collina has a number of different host plants, including the large dipterocarp resin tree, Dipterocarpus alatus. (1) These trees often have a sort of scar – a tapping hole or resin trap – in the trunk, not far off the ground, that exudes an oily resin.

Resin trap on dipterocarp tree trunk
Resin trap on dipterocarp tree trunk

The resin has a number of traditional uses, including: wood lacquering, drought-proofing of boats, water-proofing of baskets and traditional medicine.  Tapping involves cutting a hole into the trunk of the tree and using fire to stimulate a continuing flow of resin. Tapping can be sustainable, but it depends upon the skill of the tapper. (4) In sites like this one, in Chiang Dao, where these dipterocarps are the only remnants of a cleared forest, the trees will probably be more susceptible to damage and their loss as a shade would be a severe blow to the resorts and houses which exist underneath their wonderful boughs.

Stingless bees (Trigona sp.) hovering above the resin trap
Stingless bees (Trigona sp.) hovering above the resin trap

Stingless bees are called ‘channarong’ in Thai. Some species, such as T. laeviceps – which commonly occurs in suburban areas – are kept by beekeepers for their honey, which is slightly more watery and acidic than western honeybee honey (3). It also ferments. The process of keeping stingless bees is known as meliponiculture.

Stingless bees (Trigona sp.) hovering above the resin trap
Stingless bees (Trigona sp.) hovering above the resin trap
Stingless bees foraging in the resin
Stingless bees (Trigona sp.) foraging in the resin
Ants on dipterocarp tree
Ants on dipterocarp tree

Also lurking in and around the resin trap were a number of so-called resin bugs. These carnivorous assassin bugs (Family: Reduviidae; Subfamily: Harpactorinae; Tribe: Ectinoderini) coat their front legs with sticky tree resin and use this to attract and trap insect prey such as the stingless bees; a strategy called sticky trap predation. Some authors have called them living fly-paper (or bee-paper) or bee-assassins (South American genera). They really are quite strange looking insects and move very slowly.

Resin bug (Reduviidae; Harpactorinae; Ectinoderini), Chiang Dao
Resin bug (Reduviidae; Harpactorinae; Ectinoderini), Chiang Dao

There are said to be 20 species in the Ectinoderini tribe of resin bugs: ten Amulius spp.; and ten Ectinoderus spp.. The species shown here is similar in appearance to Amulius malayus but I have not been able to confidently identify it.

Resin bug (Reduviidae; Harpactorinae; Ectinoderini), Chiang Dao
Resin bug (Reduviidae; Harpactorinae; Ectinoderini), Chiang Dao

There were also one or two smaller assassin bugs, the nymphal stages of the resin bugs, which also looked to be efficient predators (below).

Resin bug nymph
Resin bug nymph

There was a very attractive spider located near the top of the resin trap.  This orb spider, Argiope pulchella, builds a web with a zig-zag stabilimentum (below). It has weaved together its web to create a much denser and thicker X-shaped cross. The spider aligns its legs against the X-shaped stabilimentum, two legs against each arm of the cross. This presumably acts to camouflage, or hide the spider whilst it is sitting on the web, and perhaps the X-shape also attract flying insects into the web. The spider moves off the cross when attending to a catch.

Argiope pulchella, builds a web with an X-shaped stabilimentum
Argiope pulchella, builds a web with an X-shaped stabilimentum

There are probably many other insects attracted to the resin trap, including moths and other sap-sucking species.  It is a fascinating little ecosystem, if that is the right word, and once again a system that is ripe with opportunities for further research.

  1. Klakasikorn, A., Wongsiri, S., Deowanish, S., & Duangphakdee, O. (2005). New record of stingless bees (Meliponini: Trigona) in Thailand. Nat Hist J Chulalongkorn Univ, 5, 1-7.
  2. Roubik, D. W. (2006). Stingless bee nesting biology. Apidologie, 37(2), 124.
  3. Chuttong, B., Chanbang, Y., & Burgett, M. (2014). Meliponiculture: Stingless Bee Beekeeping In Thailand. Bee World, 91(2), 41-45.
  4. Ankarfjard, R. (2000). Ïmpacts from tapping oleoresin from dipterocarpus alatus on trees and timber value in LAO PDR. submitted to the Journal of Economic Botany.
  5. Zhang, J., Weirauch, C., Zhang, G., & Forero, D. (2015). Molecular phylogeny of Harpactorinae and Bactrodinae uncovers complex evolution of sticky trap predation in assassin bugs (Heteroptera: Reduviidae). Cladistics.

Bluff and deception in Blues

Longbanded Silverline (Spindasis lohita)
Longbanded Silverline (Spindasis lohita)

The Longbanded Silverline (Spindasis lohita), Family Lycaenidae, is a beautiful insect with a remarkable structure – a tail, or ‘false head’ – at the end of its hind wing. There is a bright orange tornal patch – the tornus is the posterior corner of the butterfly wing – on both sides of the wing. There is also a black eye-spot and two pairs of white-tipped, filament-like black tails, or ‘false antennae’, at the end of the wing. Interestingly, many lycaenids have similar black and orange eye-spots and single or double tails.  For example, the Common Tit (Hypolycaena erylus himavantus) also has white-tipped, double tails similar to this species (1). So presumably it was a feature that evolved at sometime during the history of this family. Black and orange make a very eye-catching colour combination.

It is widely assumed that these structures are a ‘false head’ (or ‘fake head’), which acts to divert predatory attacks, e.g. bird pecks, away from the real head (and body) and towards the back of the butterfly. There is plenty of evidence that butterflies really do get pecked at, or on, these hindmost eye-spots (2). It is surprising therefore, that very little rigorous experimentation has been carried out to thoroughly investigate this phenomenon. In other words, the ‘false head’ hypothesis has not been tested scientifically. That is not to say it is not true, it is just a subject that ‘remains ripe for testing’ according to Professor Martin Stevens (3).

Long-banded Silverline (Spindasis lohita) - close-up of false head
Long-banded Silverline (Spindasis lohita) – close-up of false head

The fact that these butterflies invest so much time and energy into producing these deceptive structures and moving the little tails about like false antennae, is to my mind, quite convincing circumstantial evidence for their utility in avoiding predation, or surviving an attack. It is clear how prominent the ‘false head’ is – and might appear to a bird – when looking down on the butterfly from above (see photo below) like a bird might see it. The real head is partly hidden underneath the wings, but the ‘false head’ is very prominent.

Long-banded Silverline (Spindasis lohita), looking down from above
Long-banded Silverline (Spindasis lohita), looking down from above

The lovely wing colours of this butterfly are a tapestry, to borrow a term used by lepidopterists, of tiny overlapping scales of different colours: red, silver, orange, white and black. The scales can be seen in two excellent close-up photographs of the wings of this butterfly on this webpage (4). Males of this species also have bright, iridescent blue patches on both dorsal fore- and hind-wings. It is possible that these, together with the contrasting orange patches, could also act to startle and deter a predator and give the butterfly time to make its escape.

  1. https://rcannon992.com/2015/01/30/pushmi-pullyu-butterfly/
  2. https://rcannon992.com/2016/01/17/peck-me-here-butterfly-predation/
  3. Stevens, M. (2016). Cheats and Deceits: How Animals and Plants Exploit and Mislead. Oxford University Press.
  4. http://butterflycircle.blogspot.co.uk/2010/09/life-history-of-long-banded-silverline.html

Pretty little Anthomyiid flies

Anthomyia species fly on flower
Anthomyia species fly on flower

I am very fond of these tiny little black and white flies, which go by the rather unattractive name of Root-maggot flies. Their Latin family name sounds a bit more appealing: Anthomyiidae. There are some agricultural pests in the family, like the cabbage root fly and the onion fly, which give the others a bad name.

Anthomyia species fly on a leaf
Anthomyia species fly on a leaf

I found all of these flies close to water; by the lago San Martiño, near the Playa Morouzos at the mouth or the Ria Ortigueira. There were two main species that I came across in August at this location: Anthomyia procellaris and Eustalomyia hilaris. At least I think that’s what they were!

San Martino lagoon, Morouzos beach, Ortigueira
San Martino lagoon, Morouzos beach, Ortigueira

These little anthomyiid flies are very widely distributed across Asia and Europe and vary considerably: a taxonomist’s dream or nightmare, I’m not sure which! The first one I saw had quite large black spots and seemed to match the descriptions and photographs of Anthomyia procellaris, but I cannot be certain.

Anthomyia procellaris
Anthomyia procellaris

When I looked closely at the photograph of ‘Anthomyia species fly on a leaf’ (above) I noticed that there was a little bubble of liquid below the head. Had it been drinking or was it blowing bubbles?!

Anthomyia procellaris blowing bubbles or liquid!
Anthomyia procellaris blowing bubbles or liquid!

The next species I came across in the same location,  Eustalomyia hilaris (below), has a very pronounced black stripe running down the middle of the thorax, as well as black spots. Reportedly, this species is a parasite and its larvae develop within the larvae of bees (1). But another expert (Richard A. Jones) reports that it is “a nationally rare fly [in the UK] that breeds in the stores of dead flies collected by solitary wasps that nest in tunnels made in dead timber”. (4) Even more amazing!

Eustalomyia hilaris
Eustalomyia hilaris

I had the impression it was looking at me in the following photograph!

Eustalomyia hilaris
Eustalomyia hilaris

I relied on these excellent sites for my identifications (1, 2, 3).

  1. http://www.tuin-thijs.com/vliegen-bloemvliegen-engels.htm
  2. http://www.diptera.info/photogallery.php?photo_id=8237
  3. http://www.naturespot.org.uk/taxonomy/term/19445

Tachina grossa – a big black fly!

Tachina grossa, Galicia, Spain.
Tachina grossa, Galicia, Spain

The Yellow-faced fly or giant tachinid fly, Tachina grossa, is the largest European tachinid fly, between 1.5 and 2 cm in length. It is widespread in Europe, including the British Isles and is supposed to be a bumblebee mimic, but I am not sure which one it is copying. Probably an imperfect mimic of generally dark bumblebees. This species lays its eggs on the larvae of moths like the oak eggar (Lasiocampa quercus), on which they bore into and devour, eventually emerging as adults from the host pupa. (1) I think the yellow-buff coloured head and black body makes for a very attractive insect.

Tachina grossa, Galicia, Spain
Tachina grossa, Galicia, Spain

I came across it on elevated habitat, of heather and gorse, in hills behind Ortigueira, Galicia, Spain, on 3rd September this year.

Heather and gorse habitat in Galicia, Spain, where T. grossa was seen.
Heather and gorse habitat in Galicia, Spain, where T. grossa was seen.

 

  1. http://tachinidae.org.uk/blog/?page_id=343&q=Tachina+grossa&t=name

Saddle-backed Bush-cricket

 Saddle-Backed Bush Cricket, probably Ephippiger ephippiger cunii, male .
Saddle-Backed Bush Cricket, probably Ephippiger ephippiger cunii, male .

I came across this magnificent insect walking along a path through some pine woodland, with an under-story of heather and gorse, in Galicia, NW Spain. It is The Saddle-backed Bush-cricket. I was very excited to see one; it is absent from Britain and I had never seen one before. The closest relative we have in England, is probably the Wart-biter, which is rare. It has also been called the Mediterranean katydid, or the European bush-cricket, and is a member of the Family Tettigoniidae.

Heather and gorse habitat in Galicia, Spain, where the Bush-cricket was seen.
Heather and gorse habitat in Galicia, Spain, where the Bush-cricket was seen.

The colour patterns of insects in the so-called Ephippiger ephippiger complex, vary with geographical region as well as with rearing density. The denser the colony, the darker the brown or black markings on the tergites – or segments – on the back of the abdomen. Adults also become darker after they mature and after they have met a member of the opposite sex! (1) Some of the different sub-species have also hybridised in some areas of Europe! This makes identification problematical to say the least and as a consequence the taxonomy of this ‘complex of species’ is a bit unclear (2).

 Saddle-Backed Bush Cricket, probably Ephippiger ephippiger cunii, male.
Saddle-Backed Bush Cricket, probably Ephippiger ephippiger cunii, male.

The sexes are easy to tell apart because the female has a long, sword-like ovipositor, whilst the male (shown here) has two short appendages called cerci at the rear of the abdomen. They are flightless, with tiny atrophied wings which are used by the male to make sounds to call mates (stridulation). Not surprisingly perhaps, the songs or chirps made by these bush-crickets vary according to region; called ‘song races’ (3). The tiny wings can be seen poking out from beneath the light green saddle-back, or pronotum, in the following photograph.

 Saddle-Backed Bush Cricket, probably Ephippiger ephippiger cunii, male. Dorsal view.
Saddle-Backed Bush Cricket, probably Ephippiger ephippiger cunii, male. Dorsal view.

The subspecies which exists to the east of the Pyrenees, and I think in northern Spain, is Ephippiger ephippiger cunii, also called Ephippiger cunii. But given the taxonomic uncertainty, I cannot be sure, so if any bush-cricket experts read this, please correct me if I am wrong.

 Saddle-Backed Bush Cricket, probably Ephippiger ephippiger cunii, male
Saddle-Backed Bush Cricket, probably Ephippiger ephippiger cunii, male

A remarkably large breathing hole, or spiracle, can be seen on the thorax – just behind the fore-leg – of the Bush-cricket in the photograph below. The insect was about 25 mm in length.

ephippiger-ephippiger-cunii-male-4

The individual I came across was probably basking in the sunshine; they are nocturnal and feed at night. Going out with a torch would therefore, be a good way to find them at night. This individual was found on the hills south of Ortigueira (Galicia, Spain) on 27th August 2016.

A nice photograph of the female can be seen on this website (5).

References and Links

  1. Hartley, J. C., & Bugren, M. M. (1986). Colour polymorphism in Ephippiger ephippiger (Orthoptera, Tettigoniidae). Biological Journal of the Linnean Society, 27(2), 191-199.
  2. Spooner, L. J., & Ritchie, M. G. (2006). An unusual phylogeography in the bushcricket Ephippiger ephippiger from Southern France. Heredity, 97(6), 398-408.
  3. Ritchie, M. G., Racey, S. N., Gleason, J. M., & Wolff, K. (1997). Variability of the bushcricket Ephippiger ephippiger: RAPDs and song races. Heredity,79(3), 286-294.
  4. Kidd, D. M., & Ritchie, M. G. (2000). Inferring the patterns and causes of geographic variation in Ephippiger ephippiger (Orthoptera, Tettigoniidae) using geographical information systems (GIS). Biological Journal of the Linnean Society, 71(2), 269-295.
  5. http://www.biodiversidadvirtual.org/insectarium/Ephippiger-ephippiger-cunii-img402931.html

Bees knees and tongues!

Bombus hortorum on sea clover, Galicia, Spain
Bombus hortorum on sea clover showing long tongue or proboscis, Galicia, Spain

Since it’s Bees Needs week, I thought that I would put together a blog about bees using photographs I have taken recently in Scarborough and Spain. Taking photographs of bees is fun, but it is a bit of a hit and miss process and you need to take quite a lot of shots to get some good ones. Well at least I do! One thing that strikes one when looking at photographs of bees feeding (nectaring) on flowers, is their tongue, or proboscis. In the following photo, a common carder bee does not look like it is having any problem obtaining nectar from a Birds-foot-trefoil flower, but it might be challenged by flowers with long corollas (the tube leading down to the nectar).

common carder bee (Bombus pascuorum) on Birds-foot-trefoil
Common carder bee (Bombus pascuorum) on Birds-foot-trefoil, UK

The bumblebee tongue or proboscis is a complex organ which consists of a tongue proper – with a hairy or feathery end adapted for absorbing nectar – sheathed in a pair of palps and the maxilla (1). For a fantastic close-up photograph of a bumblebee tongue, click on the link below (link number 2) to the site of macro photographer, Adrian Thysse. The Early bumblebee, in the following photograph, has a relatively short tongue compared to some other species, but it still looks quite long in this image.

Early bumblebee (Bombus pratorum) with tongue showing
Early bumblebee (Bombus pratorum) with tongue showing

The hard, shiny maxilla which sheathes the tongue can be seen in the following photograph of a Garden bumblebee, Bombus hortorum. The tongue can be well over one centimeter long in this species (see below).

Bombus hortorum proboscis or tongue. Galicia, Spain.
Bombus hortorum proboscis or tongue. Galicia, Spain.

Bumblebees with long tongues are in general able to access nectar from a greater variety of flowers than those with short tongues, and as a consequence they feed on a larger number of species (3), assuming that they are available in a given habitat. The long-tongued bumblebees have also been found to forage significantly faster than bees of shorter proboscis length on flowers with long corolla tubes (4). Bumblebees with shorter tongues, not surprisingly perhaps, preferred to forage on flowers with short corolla tubes and were more efficient at getting nectar from them.

Common Carder Bee (Bombus pascuorum) on Sea vetch
Common Carder Bee (Bombus pascuorum) on Sea vetch

Relative tongue lengths of worker bumblebees are shown in the following table taken from the www.bumblebee.org site (1), although it is worth remembering that the glossa is a flexible and somewhat elastic organ. The data come from Brian (1957) I think (5).

Species

Tongue length mm

Bombus hortorum

12.0

Bombus lapidarius

6.0

Bombus pascuorum

7.6

Bombus pratorum

6.4

Bombus terrestris/lucorum

5.8

As well as having different tongue lengths and visiting a different range of flowers, bumblebees of different species have been found to collect a different range of pollen (6). The pollen is carried in a pollen sac, or pollen basket, which is just a flat area on the leg surrounded by a cage of spiky hairs. I am always impressed how bumblebees are seemingly able to multitask: feeding on nectar at the front end; walking with their forelegs; and scraping/combing pollen towards the basket on the rear legs, with their middle legs! The sacs of pollen look so large sometimes, the aerodynamics of the bee must change depending on whether the pollen basket is full or empty!

White-tailed bumblebee (Bombus lucorum) with pollen sac landing on kidney vetch
White-tailed bumblebee (Bombus lucorum) with pollen sac landing on kidney vetch

Another White-tailed bumblebee (below) has an empty pollen sac, and it is possible to see the fringe of hairs on the hind leg, which form the basket.

White-tailed bumblebee (Bombus lucorum) showing an empty pollen basket
White-tailed bumblebee (Bombus lucorum) showing an empty pollen basket

Another feature which sometimes becomes apparent when taking photographs of bumblebees, is the presence of tiny mites clinging on to their bodies. One can be seen, just under the wing, in the following photograph of a Common carder bumblebee.

Common Carder Bee (Bombus pascuorum) with phoretic mite highlighted
Common Carder Bee (Bombus pascuorum) with phoretic mite highlighted

These are generally assumed to be fairly harmless, in that although they live in bumblebee nests, they only feed on the detritus, wax, pollen and rubbish discarded by the bees! They use the bees as a form of transport and can get on and off as they please; a bit like getting off one bus and boarding another; the bus stop in this case, being a flower! If they cling on until the bumblebee returns to its nest, they can move home in this way. The technical term for this behaviour is called phoresis, so they are phoretic mites. They are also called commensals, which means that they are involved in a symbiotic relationship in which one species (the mites) is benefited while the other is unaffected (the bees).

Common Carder Bee (Bombus pascuorum) with mite highlighted
Common Carder Bee (Bombus pascuorum) with phoretic mite highlighted

There are of course damaging, parasitic mites, like the Varroa mite, but that is another story. The numbers of phoretic mites per bee can vary enormously and in one study ranged from one individual to over 100 per bumblebee (8); 200 per bee in another (9). Why some bees have so many, and what it means for them in terms of their health and fitness is something that is being studied, and my guess is that there is more to this relationship between bees and mites than we may realise.

  1. http://www.bumblebee.org/bodyTongue.htm
  2. http://bugs.adrianthysse.com/2015/01/in-memorium-the-tongue-that-killed-my-flash/
  3. Harder, L. D. (1985). Morphology as a predictor of flower choice by bumble bees. Ecology, 66(1), 198-210.
  4. Inouye, D. W. (1980). The effect of proboscis and corolla tube lengths on patterns and rates of flower visitation by bumblebees. Oecologia, 45(2), 197-201.
  5. Brian, A. D. (1957). Differences in the flowers visited by four species of bumble-bees and their causes. The Journal of Animal Ecology, 71-98.
  6. Brian, A. D. (1951). The pollen collected by bumble-bees. The Journal of Animal Ecology, 191-194.
  7. https://www.rhs.org.uk/science/conservation-biodiversity/wildlife/encourage-wildlife-to-your-garden/plants-for-pollinators
  8. Chmielewski, W., & Baker, R. A. (2008). Mites (Acarina) phoretic on some common bumblebee species (Bombus spp.) from the Pulawy area (South-Eastern Poland). Journal of Apicultural Science, 52(1).
  9. Matias Maggi, Mariano Lucia, Alberto Abrahamovich. Study of the acarofauna of native bumblebee species (Bombus) from Argentina. Apidologie, Springer Verlag, 2011, 42 (3), pp.280-
    292.

Tiny green metallic wasp

Yellow Dung Fly - Scathophaga stercoraria (right) and tiny green wasp (far left) on umbel
Yellow Dung Fly – Scathophaga stercoraria (right) and tiny green wasp (far left) on umbel

I took a picture of this fly, which I think is a common Yellow Dung Fly (Scathophaga stercoraria), sitting on the inflorescence of an umbelifer plant. When I looked closely I noticed that there was also a tiny little, metallic green wasp in the photograph as well (far left). There is not much to go on, but I think it is a chalcid wasp, perhaps Cecidostiba fungosa. It certainly looks a bit like the one in the photograph which was identified on the iSpot website (1).

Close up of chalcid wasp possibly Cecidostiba fungosa
Close up of chalcid wasp possibly Cecidostiba fungosa

The smallish eyes and yellow legs are the same.  There is also quite a nice photograph on the web of a very similar tiny metallic wasp with yellow legs but no identification. (2). It’s fun to come across unexpected guests and educational to try and identify them, albeit virtually!

This photograph was taken by the car park at Flamborough Head whilst I was visiting the lighthouse (Yorkshire, UK).

  1. http://www.ispotnature.org/node/126830
  2. https://uk.pinterest.com/pin/341569952964359587/

 

 

Spaced out aphids!

Sycamore aphids (Drepanosiphum platanoides) exhibiting spaced out gregariousness
Sycamore aphids (Drepanosiphum platanoidis) exhibiting spaced out gregariousness

I remember being delighted when, as an undergraduate studying zoology, I first came across the term ‘spaced out gregariousness’. This memorable phrase was coined by Professor J S Kennedy (1912-1993) and colleagues to describe organisms such as the sycamore aphid, which are gregarious – they are attracted to the presence of another aphid – but keep a certain distance between themselves. Unlike some other aphids which readers may have noticed, like the black bean aphid – which forms dense clumps – these spaced out aphids “like to be in a crowd but to have their own personal space”, to quote another aphid biologist, Professor Simon Leather (1). As we shall see, they are to a certain extent repelled by each other at a fine scale, but attracted enough to want to be as close together as they are comfortable with! (2).

How does this work? There exists around each stationary (or settled) aphid, a ‘tactile envelope’ and if any appendage of a neighbouring aphid intrudes into this space, they swing their antennae, kick their legs and sway their bodies! (2).  If all that touching gets too much for them they move away! So by a process of contact and jostling they manage to space themselves out so that they are each surrounded by a roughly circular ‘reactive tactile envelope’ – see below (and reference 2). There must be a bit of jostling and readjustment from time to time as they do need to move about the leaf and plug into new feeding sites.

Approximate 'tactile envelope' of a Sycamore aphid (Drepanosiphum platanoidis)
Approximate ‘tactile envelope’ of a Sycamore aphid (Drepanosiphum platanoidis)

Notice in the following image (within the oval) how the left antenna of one sycamore aphid (on the right) is just touching the middle right leg of the individual on the left! Presumably, this sort of touching and testing goes on all the time.

Sycamore aphids (Drepanosiphum platanoidis) close up of spaced out gregariousness with legs and antennae touching
Sycamore aphids (Drepanosiphum platanoidis) close up of spaced out gregariousness with legs and antennae touching

There is some leeway in the system though, because as sycamore aphid populations build up they become more densely spaced on the leaves, or at least there are more individuals close to each other (6). The spacing all seems to be done by touch rather than vision. Researchers found that if you cut off their long antennae they all shuffle up and end up closer together, as their shorter legs do not reach anything like as far as their antennae!

Sycamore aphids (Drepanosiphum platanoides) mainly on one side of a leaf
Sycamore aphids (Drepanosiphum platanoidis) mainly on one side of a leaf

It is apparent from the above photograph that the aphids appear to favour one side of the leaf in this case and seem to be avoiding large – relative to their tiny size – portions of the leaf. This is probably because this unoccupied part of the leaf is unsuitable as a result of being brushed by other leaves when the wind blows. The fact that the aphids would be knocked or brushed off by the regular movement of leaves in the wind, means that the space that they can occupy on favourable leaves, like this new growth, is more restricted than might at first be supposed (4). The apparent abundance of space on the leaves is therefore a bit misleading as the sycamore aphids have to sit and extract their food in a relatively safe and sheltered micro-site, e.g. within folds in the leaf (5). The micro-climate under the leaves is another factor which may determine their distribution; subtle differences in temperature or humidity may occur at a level we large humans cannot detect.

These aphids have worked out a way of being ‘solitary and gregarious’ (2) at the same time! They like their own personal space but benefit from being in a loosely aggregated group, within reach of one another but with enough space to avoid bumping legs and antennae too many times with their neighbours. Very British you might say!

To gauge the size of these aphids, the following image shows a small group of sycamore aphids on the underside of a leaf (pointing the camera upwards) with a fly silhouetted on the other, top side.

Sycamore aphids (Drepanosiphum platanoidis) spaced out gregariousness with fly
Sycamore aphids (Drepanosiphum platanoidis) spaced out gregariousness with fly

To have a very close up look at these aphids – including their different life stages – and their predators and parasites: see the following link (7).

  1. https://simonleather.wordpress.com/tag/spaced-out-gregariousness/
  2. Kennedy, J. S., and L. Crawley. 1967. Spaced-out gregariousness in
    sycamore aphids Drepanosiphum platanoides (Schrank) (Hemiptera,
    Callaphididae). J. Anim. Ecol. 36:147-70.
  3. Brady, John. “JS Kennedy (1912-1993): A clear thinker in behavior’s confused world.” Annual review of entomology 42.1 (1997): 1-22.
  4. Dixon, A. F. G. (1969). Population Dynamics of the Sycamore Aphid Drepanosiphum Platanoides (Schr.) (Hemiptera: Aphididae): Migratory and Trivial Flight Activity.”Journal of Animal Ecology 38(3), 585-606.
  5. Dixon, A., & McKay, S. (1970). Aggregation in the Sycamore Aphid Drepanosiphum platanoides (Schr.) (Hemiptera: Aphididae) and its Relevance to the Regulation of Population Growth. Journal of Animal Ecology, 39(2), 439-454.
  6. Dixon, A. F. G., & Logan, M. (1972). Population density and spacing in the sycamore aphid, Drepanosiphum platanoides (Schr.), and its relevance to the regulation of population growth. The Journal of Animal Ecology,  41(3), 751-759.
  7. http://influentialpoints.com/Gallery/Drepanosiphum_platanoidis_common_sycamore_aphids.htm

Do bumblebees know when ants are in?

Bombus terrestris queen visiting Digitalis flowers with ants outlined
Bombus terrestris queen visiting Digitalis flowers with ants outlined

I took a few photos of a large Bombus terrestris bumblebee (queen I think) visiting foxglove flowers in St. James Park, London on a fine day last week. When I looked closely at the images I noticed a few ants within individual foxglove flowers.

Bombus terrestris queen visiting Digitalis - ant outlined
Bombus terrestris queen visiting Digitalis – ant outlined

Lasius niger worker ants – and other species presumably – often tend aphids on foxglove flowers (Digitalis purpurea) and may forage for nectar on the flowers (1). But ants are not always welcome visitors to the flowers; they are detrimental to their fitness for a number of reasons (2). Firstly, they are usually too small to be much good as pollinators and secondly, their aggressive behaviour may put off more useful pollinators! They are ‘nectar thieves’ taking nectar without providing any mutual benefit for the plant, and also potentially diminishing the appeal of the flower to hard-working pollinators such as bees, which might stay away. Some plants try to keep ants away by using physical or chemical barriers, or offering them an alternative source of nectar, via extrafloral nectaries – EFNs (3). Foxgloves also have guard hairs to deter smaller bees from entering the flower (4), but it seems that ants can easily pass through these.

Bombus terrestris queen visiting Digitalis - with ant on flower rim
Bombus terrestris queen visiting Digitalis – with ant on flower rim

Does the presence of the ants affect the behaviour of the bees? Bumblebees can apparently detect whether another bee has visited a particular flower recently and thereby avoid wasting time by visiting a depleted nectar source. Do they do the same with ants? Ants do leave scent markings – e.g. pheromone trails marking a source of food – and laboratory experiments have shown that bumblebees potentially could avoid ant-visited flowers (1), if they put their minds too it! But they do not seem to use this ability much in the wild. Perhaps the ants are not taking very much nectar, so it is still worthwhile for the bee to visit the flower. Also, the bumblebees are in and out so quickly, and there are so many individual flowers clustered together on a foxglove inflorescence that it is not worth taking the time to sniff out whether ants had been in or not!

Bombus terrestris queen visiting Digitalis flowers
Bombus terrestris queen visiting Digitalis flowers

Would the bumblebee avoid a flower with an ant sitting in it? Perhaps big bumblebees like this one are not bothered by ants? Or do the ants get out of their way? Anyway, my observation was that the bumblebees were in and out of the flowers so quickly it was very hard to tell whether they avoided flowers containing individual ants. Perhaps they just steam rollered over them! Someone way know the answer to this?

  1. Ballantyne, G., & Willmer, P. (2012). Floral visitors and ant scent marks: noticed but not used?. Ecological Entomology, 37(5), 402-409.
  2. Willmer, P.G., Nuttman, C.V., Raine, N.E., Stone, G.N., Pattrick, J.G., Henson, K. et al. (2009) Floral volatiles controlling ant behaviour. Functional Ecology, 23, 888–900.
  3. https://rcannon992.com/2016/05/20/be-my-bodyguard-and-have-a-drink-said-the-vetch-to-the-ant-2/
  4. https://rcannon992.com/2015/10/25/bumbler-bees-and-foxgloves/