Beneficial Insects 



gnaws in its dead host. If a colony of aphids is examined, especially in 

 the latter part of the season, many brown and much inflated individuals 

 will be observed. These are dead, and if no hole is to be seen on their 

 backs they harbor one of these little parasites. Whole colonies of plant 

 lice are often wiped out by these little insects. 



Figure 6, Plate I, Page 11 represents a Braconid which is parasitic 

 upon cutworms. Figure 7, Plate II, Page 11 represents a cocoon of this 

 same species. 



Figure 14, Plate V, Page 19 represents another Braconid which was 

 reared from a sugar beet webworm cocoon. 



3. CHALCIS-FLIES 



(Fig. 8, Plate I, Page 11; Fig. 4, Plate IX, Page 17) 



The Chalcis-flies are among the smallest parasitic Hymenoptera. 

 Some species are not over one-hundreth of an inch long. They are 

 usually black with strong metallic reflections. Some appear quite green, 

 while others are yellow. These flies can be recognized by the lack of 

 veins in the wings (Fig. 8, Plate I, Page 11). This Chalcis-fly, as already 

 stated, is parasitic upon cutworms. (See page 44, and Figure 4, Plate 

 IX, Page 27). 



The greater part of the parasites of small insects belong to this 

 family. Some are parasitic upon scale insects. One species is the most 

 effective natural check on the cabbage-worm. 



Some Chalcis-flies are parasitic within the eggs of other insects. 



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