HYMENOPTERA 



59 



to the adult form. Of the two generations in the year, 

 the one going into the cocoon state later remains therein 

 over winter. The easiest way to study the life of this in- 

 sect is to place in a box an inch layer of quite moist soil 

 and several larva?, which must be fed twice daily for about 

 a week until they disappear in the dirt. At intervals of 

 three days different cocoons should be opened to note the 

 progress of the transformation from the larvse to the adult 

 state, occupying about a fortnight. 



The sawflies numbering two thousand species cause an 

 immense amount of 

 damage. One kind 

 defoliates the larch, 

 another the elm, while 

 the common rose slug, 

 the larva of a small 

 sawfly, causes havoc 

 to the rose bushes. 



FIG. 42. Photograph of the currant worm. 

 Natural size. 



The slimy dark-olive 



pear slug, common on 



the under side of the 



pear, cherry, and plum leaves in early summer, winters 



in a cocoon under ground and transforms to a sawfly the 



following spring. All the larva? are easily destroyed by 



dusting the plants with hellebore. 



Gallflies 



The gallflies, more properly called wasps, as they have 

 four wings, are minute insects about a quarter inch long 

 with many-jointed antennae and a chunky abdomen. 

 They derive their name from the fact that most of the 



