62 
INSECTS. 
Hover-Flies. 
the young are retained within the parent’s body, and nourished at its expense until 
the pupa stage is reached. The flies of the last category are for this reason 
generally called Pupipara. 
The family Syrphidce includes a number of species which, 
although differing considerably in external form, may be distinguished 
from other members of the suborder by the presence of the so-called spurious vein 
in the wing—a vein lying between the third and fourth longitudinal veins, and 
crossing the short transverse vein (marked in 
the figure on p. 48) which unites them. They 
also bear considerable superficial resemblance, 
both in colour and shape, to various bees and 
wasps. The best known types are the hover- 
flies ( Syrphus ), drone - flies ( Eristalis), and 
humble-bee flies ( Volucella ). The hover-flies 
of the genus Syrphus, which with their black 
and yellow bands mimic wasps, are so named on 
account of their habit of hovering in flower- 
gardens in summer, darting from blossom to 
blossom, and often sustaining themselves poised 
in mid-air, after the manner of a hawk. The 
females lay their eggs singly on leaves and 
stems infested with plant-lice; and the larvas 
devour numbers of these pests, seizing them in 
a most voracious manner, sucking them dry, and 
rejecting the empty skins. 
Like the hover - flies, drone- 
flies (. Eristalis ) frequent flower- 
gardens, where they may be seen in numbers on 
various blossoms. As their name indicates, these 
flies resemble honey-bees, the likeness being so 
close that it is difficult to persuade an uninitiated 
person that they may be handled with impunity. 
The resemblance, which is enhanced by the 
ceaseless twitching of the abdomen, appears 
indeed to be more deeply seated than might at 
first be supposed, for spiders, which recognise their prey by touch and not by sight, 
treat the drone-flies with caution. Thus a blue-bottle fly placed in a web of the 
field-spider was immediately and without hesitation seized and devoured, although 
a humble-bee was avoided by the spider, which—evidently fearing to come to close 
quarters—let out a thread, and rushing round and round its victim at a distance, 
succeeded in winding it up, and then approaching, inflicted a bite which soon put 
an end to the insect’s struggles. When a drone-fly was thrown into the web, the 
spider darted at it as before, but as soon as it touched the fly with its fore-legs, 
recoiled, as if in alarm, then returning to the attack dealt with the harmless 
victim just as it had previously acted with the humble-bee. The larvae of the 
drone-flies live mainly in ditches and feed upon decaying organic matter, and are 
Drone-Flies. 
hover-fly (Syrphus seleniticus). 
Fly ; 2, Fly hovering ; 3, Larvae devouring 
plant-lice on leaf; 4, Larva ; 5, 6, Differ¬ 
ent views of pupa. (4, 5, 6, enlarged; 
the rest nat. size.) 
