Butterfly of month -
Silver-studded Blue

Silver-studded Blue butterflies were once fairly common on lowland heaths in many parts of Britain but, with the loss of 80% of the heathland in the last 200 years, this butterfly is now classed as a “high priority” species in Butterfly Conservation's South-central Regional Action Plan.

Although small, with a one inch wingspan, they are very attractive and can be seen flying in this area at places such as Yateley Common and Hazeley Heath from early June until August.

Males usually emerge a few days before the females who, after mating, lay their eggs singly on heathers and other plants. As the emerging green caterpillars only nibble the young shoots of their foodplant, it is very important to have some pioneer heather present. It is also necessary to have Lasius niger or Lasius alienus ants nearby, as the small caterpillars are carried off to the ants' nests where they exude a sugary liquid which the ants feed on. In return the ants offer the caterpillars protection.

Pupation within the ants' nests lasts about three weeks and, when the butterflies emerge, they have to crawl to the surface to expand and dry their wings. Males have darker, leaden blue uppersides than the other “blues” and females are darkish brown with orange marks just visible around the wing edges. The wing undersides of the males are greyish, whereas they are brownish on the females with lots of black spots and silver/blue studs around the wing edges. They do not have the two spots near their bodies that the Common Blues have on their upper wing undersides.

In recent times, the number of Silver-studded Blues recorded has dropped by about 3% from year to year, so I recently met Butterfly Conservation's Regional Officer and representatives from Berkshire and Surrey to discuss how we could reverse this trend in those two Counties and North-east Hampshire.

It is very important to prevent their loss from the heathlands in Berkshire, Hampshire and Surrey so, from this year, numbers are being recorded for every known colony in the cross-border area and, by monitoring trends from year to year, we can (hopefully) identify the need for any changes in management practices at those sites.

Peter Martin

Peter Martin is the author of Blackwater Valley Butterflies a full-colour guide about the 32 different butterfly species butterflies found in the Valley.            More details >>>

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