ORDER VI.- VEIN-WINGED INSECTS. 237 



of expense and trouble might be saved to our home manu- 

 facturers. For such purposes they should be collected ear- 

 ly in the spring or late in the autumn, as those which are 

 perforated with holes would be of no use as a dye-stuff. 



The Cynips seminator is one of the smallest of the gall- 

 wasps, and yet the oak-ball, which is the consequence of its 

 puncture, is as large as a walnut, of a reddish color and a 

 rough exterior. Each one of these galls contains a large 

 number of maggots, and when it is ripe, or rather when it 

 has been abandoned by the perfect insects, it is found to 

 contain a soft, spongy, and dry substance, like a toad-stool, 

 which is easily broken and reduced to powder. 



A great number of different species of Gall-wasps are 

 found in all parts of the world, and their increase is only to 

 be desired, not dreaded, for, with the exception of the saw- 

 wasps, they do no injury to vegetation, but, on the con- 

 trary, are very useful to man ; as, for instance, those which 

 produce the oak-apples of commerce (Cynips Gallce tinctoria>\ 

 found upon the dyer's oak (Quercus infcctoria), in the Le- 

 vant. 



The ICHNEUMON-WASPS are another very useful and in- 

 teresting tribe of vein- winged insects. They are distin- 

 guished by their slender body, long ovipositor, and long an- 

 tenna?, which are always in a continual quivering motion. 

 They deposit their eggs in the living body of other insects, 

 such as grubs, caterpillars, and all kinds of larvas, upon 

 whose substance they feed. Although able to pierce cater- 

 pillars, grubs, and cocoons, yet they never use their ovi- 

 positor for defense, and consequently can be handled with 

 impunity. 



The larger ichneumons deposit only one egg in each lar- 

 va, as in the caterpillar of the Asterias Butterfly ; but the 

 smaller ones deposit several hundred eggs in one larva, as 

 we have seen in the potato-worm, from whose skin hun- 

 dreds of small ichneumons creep out, and immediately trans- 



