The weather here has been odd in October, down to 1℃ on one night recently but up to 20℃ on a few days. One one warm day last week there was a cloud of ladybirds on the south-facing wall of the warden's lodge at the nature reserve. They were all harlequin ladybirds (Harmonia axyridis) and my friend Phil J counted them - 670 - although I think he may have missed one! We saw several different colour forms.
When I got home I found about 50 on the wall of my house.
Then this week I found them on the ivy in the copse at the north end of the garden.
Alongside the adults I found several fifth stage instars (larvae),
and pupae.
One of the reasons Harmonia axyridis is so successful is that it can breed so late in the season. The larvae have to pupate and the pupae emerge as adults before hibernating this winter. Breeding is long since finished for the native species.
Harmonia axyridis is a non-native invasive species that was introduced from Asia to Europe to control aphids and has since spread to the UK. It arrived in 2003 and spread rapidly across the country, reaching the North East in 2010. It and its larvae eat aphids but will eat all sorts of other insect larvae as well, including those of our native ladybirds. Large aggregations form on warm days at this time of year, looking for a place to hibernate.
Harlequin ladybirds come in many colour forms, even though they are all the same species. The three commonest forms are f. succinea, yellow, orange or red with 0-21 black spots,
f. spectablilis, black with four orange or red markings,
and f. conspicua, black with two orange or red markings.
Ladybird, ladybird, fly away home
Your house is on fire, your children are gone,
All except one and her name is Ann,
And she hid under the frying pan.
The meaning of this nursery rhyme is unknown. For discussion of the possibilities see Wikipedia.
No comments:
Post a Comment