PROCEEDINGS OF THE THIKD ENTOMOLOGICAL MEETING 895 



it is found that this method of grouping also facilitates comparison with 

 rainfall and temperature values. 



Descriftion of plates. 



Plate 139. Various types of cages used for wood borers. 



Plate 140. Galvanised iron cages in which the air and wood humiditj' can bo 

 regulated. 



56.— NOTES ON NIGHT-FLYING DRAGONFLIES. 



By Major F. C. Fraser, I.M.S. "^ 



Dragonflies are so obviously sun-loving insects that it coines as a 

 surprise to find that there are certain species which adopt nocturnal 

 habits. 



Mr. Morton, writing to me from Edinburgk in 1917 mentioned that 

 some of the Odonata, more especially the larger Aeshnines only appeared 

 on the wing after dusk, when as a rule, they flew for quite a short period, 

 usually for about 15 to 20 minutes. A similar habit is commonly adopted 

 by some of the Sphingidse but until the receipt of the letter quoted I was 

 not aware that it was applicable to dragonflies, my exjjerience being 

 that these insects usually retire fairly early in the day and that few are 

 found on the wing after 3 p.m. 



Mr. Morton's letter induced me to make a few trial excursions at dusk 

 in the hope of securing some night-flying Indian species and as a result 

 I was able to take five of such, three of which may be said to be purely 

 night-flyers, whilst the other two, although seen on the wing throughout 

 the day, continue their activities until long after dusk, in fact until they 

 are no longer discernible in the darkness. 



Four of the species belong to the subfamily Libellulinse whilst the 

 fifth is a Gynacantha. All thus belong to the suborder Anisoptera and 

 I know of no Zygopterous species which adopts such habits. 



The following are some notes made on the five species mentioned 

 above : — • 



1. Bracliythemis contamiiwta. 

 This is one of our commonest Indian dragonflies and is seen on the 

 wing from dawn until long after dusk, apparently employing the later 

 hours for pairing as well as feeding. Both sexes may be seen hawk- 

 ing for food throughout the day apparently oblivious to one another's 

 presence, the females usually being in excess of the males, a quite con- 

 trary fact as compared with most other dragonflies ; but after dark 

 several males may be seen mobbing solitary females. 



