Lake and Pond Olive

The lake olive (Cloeon simile) and pond olive (Cloeon dipterum) are the two Cloeon species within the 51 species of mayflies in the UK. They are both quite common, especially in lowland settings, and well distributed throughout the British Isles.

The nymph of the pond olives favours smaller still water bodies like pools or eutrophic ponds although it can be found in shallow margins of slow moving rivers and streams. The nymph of the lake olive prefers larger expanses of still water like lakes although it can be found in the margins of faster flowing rivers and streams. The nymphs of the two are very similar with key differences being in gill structure. The nymphs leave the water surface in shallower water during daylight hours.

The pond olive is a small mayfly of 5 to 7 mm in size (wingspan of 13 to 25 mm). The flight period is typically March through November, although they can occur during warm periods in all months. There are often two generations per year with the one over-wintering. The flight period of the lake olive is typically April through October with the peak period being July and August. The two look virtually identical with 3 to 5 cross veins on the wing tips of the pond olive being the key visual difference (although this has little implications for fly selection). Given the similarity between the two species, they are usually grouped under the heading “Olives” when referring to them.

The nymph and dun/spinner life stages are most important to fly fishers:

• Nymph (size 12 – 16)
  • Wet GRHE
  • Wet tups indispensable
  • Wet spider
• Dun (size 12 – 18)
  
  • Dry f-fly 
  • Dry shuttlecock 
  • Dry sparse emerger with hot spot 
  • Dry shipmans 
• Spinner (size 12 – 18)
  
  • • Dry greenwells 
    • Dry rough olive

The lake olive features heavily in my Easter fishing adventures on Llyn Frongoch where shuttlecocks with a red/orange hotspot are deadly during a hatch, especially when there is a light breeze producing a slight ripple on the surface. The hatch can occur well away from the bank with the hatched flies wind-surfing the surface of the lake all the way to the bank. The brownies are very partial to tiny f-flies and shipmans buzzers during these hatches.

Prefer to tie your own, then check out these pattern options:

Tight Lines

Greg