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INSECT FRIENDS. 



VARIOUS insects are of the greatest service possible to the horticulturist — in fact, 

 without their assistance it would he almost useless to try to cultivate plants 

 at all. These insects belong to several orders, perhaps those that could least be 

 spared being 



The Ichneumon flies and their near relatives ; these insects usually lay 

 their eggs in the bodies of caterpillars, grubs, and aphides, but some species deposit their 

 eggs in chrysalides and in the eggs. These 

 insects, though called ichneumon flies, do 

 not in any way belong to the order of flies 

 proper, which are two-winged insects, but 

 they are classed in the same order as the 

 saw flies, ants, bees, and wasps, and, like 

 them, have four wings. They are nearly 

 all slender in form, and have long legs — the 

 upper pair of wings being considerably larger 

 than the lower pair — whilst the end of the 



body 



in 

 In 



\ 7«r /ft 



ICHNEUMON FLIES. 



the females is furnished with 

 some species this organ is of 



a long pointed organ, known as an ovipositor, 

 great length, being longer than the rest of the insect, and enables the possessor 

 to reach its victim, which may be a wood-boring grub, or so placed that it would 

 be inaccessible to the insect otherwise. In other species it is quite short, and may 

 be entirely hidden in the body of the insect when not in use. The ichneumon 

 flies do not try to kill their victims by piercing them with their ovipositors, their 

 only desire is to lay their eggs within them ; as soon as the grubs are hatched, they 

 begin to feed on the juices of their host. Caterpillars attacked by these parasites live and 

 feed for some time, and have been known to become chrysalides, but this effort on their 

 part is generally more than they can manage. Several of the smaller species attack various 

 kinds of aphides. One may often see on plants a large brown aphis with a swollen 

 rounded body — the result of infestation by one of these parasitic insects ; the latter vary much 

 in si/o, from insects somewhat larger than those shown in the figure to others about the size 

 of a midge. They are generally black-brown or some dull colour, though some have a 

 bright band across the body. 



The Hoverer flies (Syrphus pyrastri and other species) are very common, and may 

 often be seen hovering, apparently motionless in the sunshine, near trees or basking on 



leaves with their wings outspread. Their grubs are 

 most voracious, and feed entirely on aphides. They 

 are quite blind, though, having neither eyes nor legs, 

 they manage to kill an enormous number of aphides. 

 They cling on to the leaf or stem on which they 

 are by means of certain tubercles near the end of their 

 bodies ; raising their heads and the first few joints of 

 their bodies, they strike about until they touch an 

 aphis, when they immediately seize it, hold it up in 

 the air, and suck the contents of its body completely 

 out, which is only the work of a minute and a-half. 

 They then turn their heads on one side, drop the 

 empty skin, and at once search for another aphis. These grubs are about Jin. long, the 

 widest part being at the tail, and gradually taper to the head. Their mouths are furnished 

 with a double hook, with which they secure their prey ; they are of a greenish or yellowish 



/. Sctzva balteata. 4, Scczva pyrastri. 7. Scceva ribesii 

 2 and 5. Gru^s. 3 and 6. Chrysalides. 



