128 
PSYCHE 
[October 
Ilaliday states that Cule.v detritus* occurs at Holvwood, County Down, “in mul- 
titudes, during the day among hedges on the seacoast, in the evening in columns 
about the tops of trees, appearing like smoke at the distance of a furlong.” Weyen- 
bergh records two swarms of Culex pipiens from the vicinity of Haarlem, observed 
in 18.57, dancing in jierpendicular columns. 
Mott gives an interesting account of an unusual gathering of gnats observed by 
him in 1879. As the article is not generally accessible and describes well the j)henom- 
enon, I quote it nearly in full. “On the evening of September 1st, between si.\ and 
seven, after a fine, sunny day, the sky being clear, and the full moon just rising as the 
sun went down there was a grand festival among the gnats. Above the tops of the 
trees and hedge-rows in the low meadows north of Leicester these little Diptera were 
out in immense numbers. * * They assembled in groups of various shapes, some- 
times a vertical column from 6 ft. to 20 ft. high, and 1 ft. to 3 ft. diameter, rose from 
a tree top like a pillar of smoke. Sometimes a sheet 4 ft. or 5 ft. high and 10 ft. long 
hung above the hedgerow, Imt seemed never more than a foot or so in thickness. 
The following evening, at the same hour, the sky being more clouded, a few gnats 
only were to be seen; but on the evening of the 6th, with the sky again cloudy, there 
was a still more remarkable display of gnat life. The little creatures were out again 
in millions, but this time the vertical column formation was adopted by nearly the 
whole of them. These columns rose from the hedges on either side of the road, and 
were visible for half a mile a-head at irregular distances, averaging, perhaps, 21 ft. 
or 15 ft. They formed an avenue of such a singular and unusual appearance that 
everyone who passed along the road paused at intervals to watch and womler at them. 
This ])iece of road is about half a mile long, on the top of an embankment which 
carries it over the low meadows and the river. At the farther end there are a num- 
ber of trees, and from the top of nearly every tree three or four of the strange, smoke- 
like columns could be seen standing up in the air, always straight but not always 
vertical, some of them being inclined at small angles. * * On watching one of the 
columns closely, it was a]iparent that all the gnats had their heads one way, facing 
the breeze, whieh, however, was a very light one. It was a calm evening; what air- 
current there was came from the south-east. It seemed to be sufficient occasionally 
to pre.ss back the column a few inches from its normal position, and whenever this 
happened the whole body of gnats jerked themselves forward again with one per- 
fectly synchronous impulse.” 
A picturescpie account of a remarkable swarming of Culices, at Lewisham Road 
* Haliday’s Culex detritus greatly resembles the common Culex pipiens and most probably the 
observation should be credited to the latter species. 
