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Another week of varied weather; chilly and wet on 8th-9th, showery on 10th; sunnier and warmer on 11th, wet on 12th, sunny and warm on 13th and wet again on 14th! On Tuesday the Blue House volunteers carried out the annual Water Vole survey on the reserve. It was not easy this year as whereas, normally, we are able to walk along the water's edge on the fleets looking for latrines, this summer the water's edge was often half way across the adjoining field! One of the problems the reserve has is Azolla, the Water Fern, a native of South America. During the summer months some years it chokes several of the ditches, forming a dense mat on the surface which, in autumn, dies back to leave a disgusting brown sludge. It has a reputation for appearing in an area, flourishing for a few years, then disappearing as quickly as it came. Unfortunately, that has not been the case at Blue House, where it has been a problem since the EWT purchased the reserve twelve years ago. Capybara may be able to swim through it but Water Voles cannot and they vacate those ditches that are infested with it. For instance, one ditch, on the Flat Fields, often produces a count of 80-100 latrines in the hundred metres surveyed each summer; last year, and again this, there were none. Despite this, there still appears to be a healthy population on the farm.

You have to keep your wits about you when wading through the reeds less you barge into a Reed or Sedge Warbler's nest and tip the eggs or young into the water - not an ideal scenario on a nature reserve! You often come across other things of interest too, though, which today include the Horse Hair Parachute Marasmius androsaceus, growing on old reed stems, and these two caterpillars, a Brown-tailed Moth (above) and Reed Dagger, below.

The warm and sunny weather on Friday enabled me to carry out my weekly butterfly transect on the reserve with some hope of seeing a few! The cold, wet spring had a disastrous effect on many of the single brooded species that appear then but the summer grassland species appear to be doing well, despite the fact that a thin film water still covers large parts of the flatter fields, even this late in the summer. The one exception is the Common Blue : numbers peaked at around 500 in 2010, crashed to a maximum of 23 last year, while this summer I have not seen more than two together! However, on 13th and the week following, there were counts of 950 Meadow Brown, 300 Gatekeeper, 230 Small Heath and 44 Small Copper, the last two species reaching record levels on the reserve since regular transects began in 2007. There is plenty of grass for their caterpillars to feed on, or in the case of the Small Copper, Sheep's Sorrel, and in places I was struggling through a knee high mat of clovers, vetches, tares, vetchlings and other flowers including these, ahem, Strawberry Clover, a scarce species in Essex which seems to be found mainly along the coast. Another species which appears to be thriving in this area is the much rarer Sea Clover, which I did not photograph!.

Catches in the moth trap on the reserve also continue to improve and included a fine, late brood, Early Thorn this week.

Finally, this Longhorn Beetle Stictoleptura scutellata was snapped at The Backwarden. It appeared to emerge from the log pile near the fire site and landed on an oak nearby. Apparently it is quite a rare species but has recently been spreading its wings from its Essex HQ, Epping Forest. The identification was confirmed by both PH and Peter Hammond.