Thursday 9 July 2009

An unexpected humming visitor

Yesterday, while taking photos of the resting Wool-Carder bees, I was nicely surprised by the low humming noise coming from a Hummingbird Hawkmoth, Macroglossum stellatarum. It was feeding high up in the blossoming buddleia. Fortunately I had the camera with me (I don't let it out of my sight these days!) and managed a few shots. The one on top is the best. Like the Painted ladies and silver Y moths, they are migrating insects from southern latitudes, which tend to come in warm weather and tend to appear on the same summers.
Graph showing my local records for three migrant species as year totals. The scale is logarithmic and I have replaced 0 by 0.1 to allow for this.
Hummingbird Hawkmoths take their name from their hovering flight. As other hawkmoths, they have long proboscides and do not land on flowers to feed, but just hover in front of them, darting sideways to the next bloom. They are active during the day and at dusk, which makes them easy to observe, unlike many nocturnal moths, including some of the same Hawk-moth family (Sphingidae). Hummingbird hawk-moths have fast flight and small wings, so, due to their high energy demands they prefer nectar rich flowers. My records are in Buddleia, Caryopteris, lavender, Centrarthus ruber and Ceanothus.
Hummingbird hawk-moth feeding on buddleia at sunset (Sep 2003)
 Hummingbird hawkmoths have been the subject of learning experiments carried out by Almut Kelber regarding flower colour and design. They are as good learners as bumblebees, much better than the butterflies tested, which had strong innate preferences. Although the hawk-moths have a innate preference for blue flowers, they are eager to try new colors and easily learn to associate different colours with food rewards. Given that they are relatively long-lived (up to 4 months in the laboratory) and strong migrants, this flexible learning behaviour might give then the ability to sustain their high energy requirements from different, seasonally or locally changing flower resources.
 If you have any records, Butterfly Conservation is carrying out a survey: Migrant Watch - Hummingbird Hawk-Moth.

1 comment:

Antje said...

Interesting to see a statistic - I've only seen one of these this year, whereas they had been quite abundant the years before. They always make me dart inside to get my camera. :-)