106 
THE ORDER OF COLEOPTERA. 
[ Fig. 48. ] most distinctive character is the 
extension of the thin thoracic 
'mf margin, which is narrow in the 
|1\ other sub-families, but is here ex- 
\ panded so as, in most cases, to 
j completely cover the head. It is 
in this sub-family that we find 
PuoriNOB rvitAus, Linn.:-common firc-dy; or , more t h 6 species remarkable for their 
properly, Lightning-beetle l a, larva;/, e, a , head, i- 
under side of segment, and leg of same ; f>, pupa in its ] um i uous Or phosphorescent pi'O- 
earthen cell ; c, beetle— alter Riley. x * 1 
perty, which is possessed by no other insects except a few of the Elate- 
rid;e.* This property is located in one or more of the segments on the 
under side of the abdomen. The luminous power is intermittent, being 
exhibited by flashes, and is evidently controlled by the will of the insect. 
It is a vital phenomenon, and consequently ceases after death; but the 
luminous segments can be distinguished in the dried specimen by their 
uniformly yellow color. 
The historic and poetic glow-worm is the wingless female of the Euro- 
pean Lampyris noctiluca , Linn. But iu most of our species both sexes 
are furnished with wings. 
The Lampyrides are nocturnal insects, being sluggish by day, and 
found sometimes on the ground, and sometimes resting upon the foliage 
of trees, or upon the palings of fences. But at night they launch out 
upon the wing, sometimes in immense numbers, especially in low mea- 
dows, which they illuminate with their multitudinous flashes of phos- 
phoreseuce. 
The following are the principal genera: 
A. Elytra complete, except in some wingless females; head wholly or partially covered by the 
thorax. 
B. One or more ventral segments, pale yellow, and luminous in the living insect. 
C. Antonme dilated and compressed ; the abdominal segments of the males lobed at the sides ; the 
last segment only luminous Lucidota, 3 sp. 
C C. Autenmc slender ; the abdominal segments simple ; one to three last segments luminous : 
Photinub, 26 . 
A A. Elytra much abbreviated and attenuated ; head exposed ; antenme branched ; phosphoresonco 
uncertain Piiknciodks, 2. 
The Lucidota atra, Bab., supposed to be the same as the laticornis 
of the same author, is a common iusect. It varies from three to four- 
tenths of an inch in length, and is of a deep black color, with the mar- 
gin of the thorax pale yellow. The genus Pliotinus , Laporte, contains 
most of our lightning beetles. The P. pyralis , Linn., (Big. 48,) is half 
an inch or a little more in length, blackish, thorax with yellow margin 
and red disk, with a blackish spot in the center ; the elytra have a nar- 
* We should perhaps also except the Fulgora lanternaria of S. America, and the F. candclaria, and 
the Bupreetis occllatct of China, and a few other insects which have been reported to possess luminous 
properties. But the testimony with regard to all of them is very conflicting, oven with respect to tho 
Hist mentioned, the lumiuousuess of which bus been generally believed. 
