Diplosis botularia. 



The large pinnate leaves of the ash may be seen in any 

 wood during summer time. Diplosis botularia [attacks the 

 leaves of saplings more frequently than those of trees. On some 

 rachides there may be as many as thirteen leaflets, and each one 

 will be galled ; it is not usual, however, to find such specimens, 

 the general number being nine or eleven. Towards July and 

 August it may be observed that these leaflets are considerably 

 thickened along the under surface following the course of the 

 mid-rib. This thickening is caused by the presence of the 

 larvae. The ova are laid on the upper surface of the leaf 

 along the plane of the mid-rib, and when the larvae hatch, 

 they cause the mid-rib to rise up on each side of them, and 

 with it also the blades of the leaf, 'until portions of the latter 

 approximate. When this is completed, the continued swell- 

 ing of the mid-rib causes the leaflet to curve and its free 

 edges to wrinkle. 



The length of the galled portion depends entirely upon 

 the number of larvas within it. A leaflet 70 mm. long may 

 contain six or eight larvae. One leaflet examined by the author 

 measured 98 mm. long and was galled throughout its entire 

 length. It contained eighteen larvae. 



The interior is divided into larval chambers, which vary 

 in size according to the age of the larva. Some cavities are 

 8 mm. long by i| mm. broad. When the leaves begin to 

 wither, small cracks appear at the thinnest part of the cell- 

 wall, and through these the larvae escape and fall to the 

 ground to pupate. 



The illustration is of specimens gathered at Hastings by 

 the author. 



