n8 * The Scottish Naturalist. 



The pupa is shorter and stouter than the larva, and the 

 abdomen is more sharply pointed. At first it is white, but 

 after a day or two assumes a yellower hue ; wing-cases, limbs, 

 and proboscis white; eyes black. At the commencement of 

 the pupal state, the proboscis is pressed -rather close to the 

 breast, but afterwards projects more from it. The limbs are laid 

 along the breast. When touched or alarmed the pupa moves 

 the abdomen about in a rapid and irritable manner. The 

 larvae rarely spin a cocoon in confinement, but occasionally they 

 spin a rough one. 



The larvae are found in the galls from the end of June to 

 the end of September. Several broods appear to occur in a 

 year. The development of the insects will occupy about seven 

 weeks. In some localities near Glasgow I found that fully 

 forty per cent, of the galls were occupied by them ; on the 

 other hand, in some places they are not found at all, so that 

 the total per centage of sawfly larvae destroyed by them will be 

 much smaller than that. 



How does the weevil contrive to get rid of the proper tenant 

 of the gall ? Upon this point, I was unable to make any direct 

 observations, but am strongly inclined to believe that it is dis- 

 troyed in the egg, or at anyrate when a very young larva. 

 This conclusion is based upon the following facts. I have 

 found in a gall a very young weevil larva, and on the same 

 leaf was another gall in which was an egg of galiicola. In 

 another instance the two species were found living in separate 

 galls on the same leaf ; they were both in the first moult, but 

 the weevil larva was clearly further advanced in its develop- 

 ment than the other. These facts seem to point to the con- 

 clusion that the growth of the weevil is more rapid than the 

 saw-fly, and they have been found shortly after the galls have 

 arrived a maturity. Although I have examined some hundreds 

 of galls never in a single instance were the two found 

 together, and when a young weevil was placed in a gall with a 

 saw-fly larva, and the gall carefully closed, it shortly afterwards 

 cut its way out, leaving the other uninjured. 



It is therefore evident that the inquiline being stronger, and 

 coming to maturity fast :v than its companion, kills it, perhaps 

 unconsciously, by its e.urgetic manner of feeding. The eggs 

 appear to be also deposited in galls where the larvae are about 



