SEASONS OF INSECTS. 518 
appear only during the twilight, whether in the morning 
or evening; but the term may be understood, with some 
latitude, to signify all those insects that are seen only in 
the morning and evening, though after sunrise and before 
sunset. Of these, some come forth only in the morning, 
others only in the evening, and others both morning and 
evening. My memory only furnishes me with a single in- 
stance of an insect whose principal appearance and flight 
are in the morning. Hemigeometra nupta Haw. I have 
often seen flying at this time, about six or seven o’clock, 
and never at any other: I am not however prepared to 
assert that it does not appear in the evening or night, 
but I have then never met with it. In the evening more 
particularly you hear the hum of the dung-beetle (Geo- 
trupes Latr.), which Linné thought the prognostic of a 
following fine day; and of the swarms of Melolontha vul- 
garis and solstitialis. Then also many other Coleoptera 
are in the air; especially before a thunder-storm, a state 
of the atmosphere that particularly excites insects? : P¢7- 
nus imperialis and germanus I have never taken except 
under these circumstances. ‘Then the Ephemere sport 
in the air, and lead their mystic dance. The majority 
of the hawkmoths are then too on the wing, with their 
long tongues imbibing the nectar of the flowers while 
they hover over them, both morning and evening. 
iii. In the nzgh¢ the main body of the moths take their 
flight, as well as a vast number of Coleoptera and insects 
of other orders. At this time the Blatie and crickets leave 
their hiding-places and run about: but the other Gryliz 
L., though they sing in the night, fly only in the day. 
* See above, p. 246 -. 
VOL. IV. 21 
