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A week has passed during which the rains slowly abated (at least for part of each day). Dryer vegetation means that our nets (and ourselves) don’t rapidly become water-sodden and we can catch insects more easily and effectively. Whenever the weather has allowed, we have been climbing through the forest searching for flies and enjoying a good measure of success in our quest.

Many of the species we have been catching belong in genera with which we have little familiarity; being rare and little-known, even to specialists such as ourselves. Finds such as these make all the hard slogging up precipitous slopes, cutting through dense vegetation, deep sucking mud and scratches and bites from a myriad of thorny plants and man-eating insects worthwhile! I guess you have to be a shade unhinged to enjoy this sort of thing. . . or a field entomologist perhaps?

Our time at Estación Científica San Francisco is now drawing to a close and tonight we have been sorting and labelling our samples carefully to ensure they are ready for shipment back to our bases in Cardiff and Manaus. Proper field curation of collected specimens is a vital part of expeditions such as ours, ensuring that all data (where/when an insect was captured, what it’s habitat was and how it was behaving etc. etc.) is properly cross-referenced with the actual samples. Were the samples to become detached from their data they would be rendered useless, of mere cosmetic interest.

To read more about Adrian's travels, go to our Natural History blog page

We have made it to the Estación Científica San Francisco in Podocarpus National Park, Loja Province. Well, we made it but one of our bags didn’t, apparently having been left behind in Quito. We are hopeful that it will arrive tomorrow in Loja and we can arrange for a taxi to bring it the hour or so’s drive to the Estación. Meanwhile we are getting to know our new home for the next week.

The Estación is perched on the side of a narrow ravine in dense forest through which flows the Rio San Fransisco. All our routes into the forest start with a spectacular crossing of the river using a wire cradle suspended from a rope running through pulleys at either end high over the water. Progress is made by pulling hand over hand on the opposing rope until the other side is reached. Once over, the ground is very steep and densely forested. Our intial forrays into the near reaches of this wilderness indicate a spectacularly diverse fly fauna. . . and that is what we are here for. We have set our Malaise traps but the incessant rain is making other fieldwork difficult so we will have to wait for better weather to get further afield and explore more.

You can read more about Adrian's travels on our blog page

Having completed our work at Yanayacu we have moved further down the eastern slopes of the Andes to the town of Tena in Napo Province. Here at only 500m above sea level it is much hotter than in the mountains - a truly tropical climate. The town is placed on the last slight hills before the Andes sweep down and merge onto the flatlands of the Amazon Basin. West of here, the rivers are fast and furious having dropped 3000m or more in just 50km through the mountains whereas to the east they become sluggish and it will take another 3000km for them to drop the remaining 500m to the sea.

Our visit to Tena is necessary to complete administrative formalities and to obtain permits allowing us to move the specimens we have collected between different provinces within Ecuador. After three visits to the Ministry of Environment, numerous phone calls, support from a well-connected colleague at the newly established university in Tena and from colleagues in Quito we are still waiting for a positive outcome!

Josenir and I have to move on to our next study site in Loja Province and we have no chance or getting the permits through in time. Fortunately, Eduardo has to remain in the town to deliver a 3-day entomology course to the students at the university. The hope is that he can complete the formalities and bring our specimens with him when he moves back to Quito next week and we can take them from him when we pass through Quito on our way out of the country. Meanwhile Josy and I have a plane to catch….

Find out more about what Adrian has been up to by reading his past blogs.

Our time at Yanayacu has drawn to a close. The final days fieldwork saw us collecting in the Malaise traps we had previously set and making several forays to a particularly good stream site where we had hoped to find more species of Hemerodromia. Hemerodromia is the focus of Josenir’s PhD work at INPA and we have been searching hard for specimens to help her studies.

Alas, many hours of wading up streambeds, sloshing through mud and slithering over mossy spring sources has yielded but a handful. These will be valuable for her studies but we can’t help but feel a bit disappointed by the results on this aspect of our expedition. We have speculated long and hard as to why Hemerodromia has been so hard to find. Perhaps these aquatic insects have been washed out of their streams by the unusually strong rains we are experiencing? It seems that a particularly strong El Nino event has commenced bringing late rains throughout Ecuador.

During the evenings we have been running an ultraviolet light to attract nocturnal insects to the Biological Station. A couple of nights ago we were absolutely inundated by insects with vast numbers of hawk moths, tiger moths, giant Hercules beetles and enormous stoneflies (Plecoptera) known as Dobson Flies in the US, coming to the light. It’s odd but the best nights for attracting insects are not warm balmy ones but those with torrential rain and enveloping cloud. And such were the conditions on this particular occasion.

To read more about Adrian's expedition - read his past blog posts.

We have now settled into a routine at the Yanayacu Biological Station. Our days are spent out in the forest collecting flies and in the evenings we examine the results of the days efforts, preserving the specimens and collating data about where and how we found them. Josenir and I are especially interested in a group of flies known as Hemerodromiinae and in our fieldwork efforts we mostly target streams, rivers and springs where we expect to find them.

The terrain in this part of the Andes is generally very steep and many of the stream banks have washed-out and slipped allowing a dense understorey of bamboo to grow. Because of this, simply getting into the streams can involve much machete work hacking through the vegetation and a slithering half-controlled descent of muddy slopes until we finally splash into the stream bed and can begin work. Our general procedure is to wade upstream using a net to sweep insects off surrounding vegetation, or selectively picking flies off wet rocks, wet moss etc. It is hard, dirty and wet work and we inevitably return soaked to the skin and mud-splattered but we have been rewarded by many interesting finds.

Yesterday we found perhaps 30-50 species (it’s not really possible to be more precise until we begin detailed examinations back in Cardiff and Manaus) and we think that around 90% of these will be completely new species that have yet to be described. I was particularly delighted to find no less than 5 new species of the genus Chelipoda. I have studied this genus intensively in the past and attempted to construct a ‘phylogenetic tree’ showing the systematic relationships between the living species and inferring the sequence of their evolution.

It is not yet clear if most South American species of Chelipoda evolved from ancestors that migrated south from North America in the distant past or if they have developed from so-called ‘Gondwanan’ species - ones which originated on the ancient supercontinent of Gondwana before it broke apart and its fragments drifted apart to form modern day New Zealand, South Africa and Patagonia for example. Careful examination of the Ecuadorian species should reveal clues hidden in their anatomy as to which theory (if any) is correct.