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INSECTS

The larva of the dainty green lace-wing fly (Chrysopa ram-burii) is often called the aphis lion because of its habit of preying upon this pest. The larvae are drab in colour, slender, and about one-third of an inch long. They have very active legs and a pair of large toothed jaws. They are easy to find at night among aphides or prowling over rose plants in search of food, which also includes scale insects. In the daytime they usually hide among the petals of blooms. The fly is a beautiful light green with delicately patterned lacy wings and con­spicuous bright-yellow eyes. Great numbers fly or rest round lights at night in warm weather.

The hover-fly or syrphid (Syrphus viridiceps), in the caterpillar or maggot phase of its life cycle kills a tremendous number of aphides.

This larva is grey-green, About one-third of an inch Broad. It some what resembles the harmful leaf-curling caterpillar, but differs in that it moves slowly, does not attempt to escape or conceal it self when touched, is harder, and little broader. It is most common is spring and autumn.

Wasps vary greatly in their life histories; some are almost fantastic. The female of some species has, at her rear end, a long, then, sharp append age called an ovipositor. She injects this into her prey, which she has already stupefiled, and there deposits her eggs. On hatching, the larvae feed the body tissues of the host unil fully grown, when the host dies and the larvae emerges as insects. One minute wasp lays her egges within the aphis. As the larva grows the aphis skin becomes hard and metallic in appearance. That aphis is past doing harm to roses and shelters a young wasp, precious to the garden, for it will very soon deposit an egg within the body of each of hundreds of aphides. Never destroy aphides that have this unusual appearance. Other species stun, im­pregnate with ova, and remove caterpillars several times their own weight.

The spotted ladybird beetle (Lets conformis), lays its eggs on aphis-infested plants, and the young (often called "niggers"), on hatching, despite their small size, will destroy aphides at the rate of thirty or forty an hour.

The mantids are always given credit for destruction of pests. There are many species varying in colour from green to brown, and in size from half an inch to three inches in length. Some of the smaller types attack aphides. The larger

Fig. 19. A wasp parasitizing a cut-worm.

(Drawing by R. T. M. Pescott.)

varieties destroy bees and other desirable insects just as com­monly as beetles, moths, and flies. They even resort to can­nibalism. The egg-cases, found on almost any structure or hard-wooded plant, are small, brown, rectangular mounds with sloping sides. The upper aspect is marked by two rows of small circular indentations. Each of these is the covering of a cell containing an egg. The young mantid forces its way out through the disk.

Since modern insecticides have been used for spraying in the last few years, it is noticeable how some garden pests that are not killed by them have increased in numbers, especi­ally red spider and pea mite. This is due to these compounds killing insects that are enemies of these pests.