BENEFICIAL VERSUS INJURIOUS INSECTS. 
of insect control. We have records of many insects at work controllng 
injurious insects, but this is almost entirely the work of nature. The 
controlling hand of man has not taken part to any extent. The most 
important entomophagous insects belong mainly to the orders Hemi- 
ptera, Hymenoptera, Diptera, Neuroptera, and Coleoptera. 
The Coleoptera include ladybirds (Coccinellidw), murky ground 
beetles, and tiger beetles. The ladybirds feed upon small insects and 
the eggs of larger species, and are especially valuable for keeping down 
plant lice (aphids). . Their larve also are quite active, and hunt for 
their prey. The ground beetles (Carabide) destroy large numbers of 
caterpillars of various kinds. They hide under stones and boards in 
the day time, but leave their shelters at night time seeking what they 
may deyour. 
The Hymenoptera include many important parasites belonging to 
the families known as the Ichneumonide, Braconide, and Chaleididx, 
all very small wasps. Also included in this order are the smallest of 
all parasitic insects, the Proctotrypide. Their larve live within other 
insects, often in the eggs, and sometimes within the larve and pupe. 
Sometimes they occur as secondary parasites, and as such have to be 
eliminated from the primary parasite before the latter can be employed. 
Caterpillar of Army Worm with Tachinid Eggs attached. 
Several families of the Diptera are either parasitic or predatory. 
Two of the best known are the Tachinide and the Syrphide. The 
Tachinids are bristly flies, closely related to ordinary houseflies. They 
parasit'ze many kinds of caterpillars and grubs of large sawflies and 
immature grasshoppers. They attach their white eggs to the surface 
of caterpillars, especially eutworms (plant destroyers), with a gummy 
secretion. In other cases, they insert their eggs within the bodies of 
their victims, or deposit them on leaves which form the food of their 
hosts. The eges are thus taken into the digestive system. They are a 
most useful group to the agriculturist. The Syrphids, or flower flies, 
are large, and often bee-like in form, and lay their eggs in colonies of 
plant lice, which are later on devoured by the larve that hatch out from 
the Syrphid eggs. These larve fead exclusively on aphids and 
plant lice. ; \ 
The Hemiptera include many of the well known bugs (assassin, 
stink, damsel, ambush, and others), of which there are some beneficial 
forms, in addition to the many injurious ones. 
_ The Neuroptera include forms known as aphis-lions or lace-winged 
flies, which are predatory on many plant lice. “a 
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