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 SOME BENEFICIAL HEMIPTERA OF QUEBEC 



P. I. Bryce, Maodonald College, P. Q. 



Although the order of four-winged sucking insects known as the Hemiptera 

 contains perhaps the most injurious, and numerically by far the worst of our 

 pests, some of the True Bugs are beneficial to the farmer. The benefit is of 

 course indirect, for the value lies in the destruction of noxious insects. Some 

 are only partly predaceous in their habits and feed both on plant and insect juices. 



The predaceous bugs show a wide variety of form, which agrees with their 

 diverse habits. Some skip over the surface of ponds and quiet bays, others swim 

 beneath the water, or live far out at sea. j\Iany are marsh dwellers, aad lurk in 

 shady spots on the look-out for their unwary fellows. None is more peculiar 

 thati the bug which n:a.^ks its presence v/ith a coating ot small particles of dust, 

 while il watches j"or bed-b'igs, flies or other insects. To most of 3'oii, however, 

 there are some very much better known. The large slow-moving green bugs 

 sometimes seen on berry bushes, though injurious themselves, have close rela- 

 tives which are very useful. Several, both useful and destructive forms, similar 

 to the green plant-bug, bellong to the Pentatomids or Stink-bugs. They are broad, 

 flat, often with a spine on each side of the mid-region or thorax, and have 

 thicker upper and thinner transparent under wings. On the head are two five- 

 jointed feelers, and between them projects downward a sharp piercing beak, tube- 

 like, and used for sucking plant or animal juices. Many such bugs are protected 

 by evil-smelling and vile-tasting secretions of certain glands. Berry pickers know 

 very well why these are called "Stink-bugs". 



Of the few of these malodorous bugs helpful to the plant-grower, Mr. E. P. 

 VanDuzee mentions as occurring in Canada several forms. They feed on a var- 

 iety of insects, both larvae and adults. While some seem to be general feeders, 

 others more fastidious limit themseilves to a few species as food. Several feed 

 in part on insects, and also on plants. In both cases the juices of the host are 

 pumped up through the jointed beak thrust into the tissues attacked. The insect 

 prey is literally sucked dry. 



Among the insects fed upon are the Colorado Potato Beetle ("the Potato 

 Bug"), Flea Beetles, Cabbage Worms, Cutworms, Tent-caterpillars, Fall Web- 

 worms, the Eight-Spotted Forester Moth, and the Tamarack Saw-fly. They also 

 feed on the true bugs, on the beneficial Lady-bird Beetles (Lady-bugs), or they 

 may turn cannibal and eat their kind. 



Perhaps the most useful Stink-bug is the Perillus (Perillus circumcinctus, 

 and P. bioculatus) which feeds on the Colorado Potato Beetle and other beetles. 

 Both young and old potato bugs are preyed upon, and the young nymphs and 

 the winged adults of Perillus alike help in the destruction. In an account written 

 in 1871 we read that the bug "attacked the Colorado beetie larva with a sudden 

 dart of its sharp-pointed beak and sucked out the contents of the body". Perillus 

 was taken at ^^lontreal. 1902; Ste. Anne's, 1909, and was common in five counties 

 of Ontario where it was collected in 191 1. It was there feeding on the eggs, 

 young, and adults of the potato beetles. In some fields of unsprayed potatoes 

 scarcely any beetles were found, because of the activity of the Perilius. The insect 

 is 5-16 in. long, 5-32 in. wide, and easily told by the white margined, brown wedge, 

 the scutellum, which projects back over the wing covers. The general color is 



