358 THE TANYSTOMA. 



cannot suppress the cravings of their appetite^ and 

 when these insects are seen paired (by no means an 

 uncommon sight in the spring and summer months), 

 the female is almost always found holding some little 

 fly in her fore-legs, turning it about, and as it were 

 mumbling it over all the while that she submits to the 

 caresses of her partner. It seems not improbable, 

 indeed, that the latter may always select the auspi- 

 cious moment of the capture of a prey for the purpose 

 of paying his addresses, from a presentiment that 

 should he venture to approach when the weapons of 

 the object of his affections were not otherwise engaged, 

 he might stand some chance of being sacrificed, — not 

 jon the altar of Venus. 



The Dolichopi and their allies are small flies usually 

 adorned with metallic colours, which, in many respects, 

 and especially in the structure of their antennae, con- 

 sisting of three joints and a long bristle, seem to 

 approach the third tribe of this suborder of Diptera. 

 They are usually found on the borders of water, and 

 many of them can even run with ease upon the sur- 

 face, capturing their prey in the same way as the 

 common long-legged Hemipterous Boat-flies (Gerris), 

 to which I shall have to refer hereafter. 



If all the Tanystoma used the powerful weapons 

 with which they are endowed by nature only in the 

 destruction of their weaker brethren, we should have 

 but little personal interest in their proceedings, but 

 we have already seen that the Asili are suspected of 

 employing their formidable mouths in sucking the 

 blood of cattle; and although it is still a matter of 

 doubt whether those flies are really guilty of the 

 offence imputed to them, there are several species 

 whose blood-sucking propensities are but too well 



