PLANT LICE
which has no distinct head but from which is protruded and retracted a pair of strong, dark hooks. Watch one of these things as it creeps upon an unsuspecting aphid; with a quick movement of the outstretched forward end of the body it makes a swing at the fated insect, grabs it with the extended hooks, swings it aloft kicking and struggling, and relentlessly sucks the juices from its body (Fig. 105). Then with a toss it flings the shrunken skin aside, and repeats the attack on another aphid. This heartless blood-sucker is a maggot, the larva of a fly (Fig. 106) belonging to a family called the Syrphidae. The adult files of this family are entirely harmless, though
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Fig. 106. Two common species of syrphus flies whose larvae feed on aphids.
(Enlarged about 3¼ times)
A, Allograpta obliqua. B, Syrphus americana
some of them look like bees, but the females of those species whose maggots feed on aphids know the habits of their offspring and place their eggs on the leaves where aphids are feeding. One of them may be seen hovering near a well-infested leaf. Suddenly she darts toward the leaf and then as quickly is off again; but in the moment of passing, an egg has been stuck to the surface right in the midst of the feeding insects. Here it hatches where the young maggot will find its prey close at hand.
In addition to these predacious creatures that openly and honestly attack their victims and eat them alive, the aphids have other enemies with more insidious methods of procedure. If you look over the aphid-infested leaves
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