.20 MAINE AGRICULTURAL EXPERIMENT STATION. I9II. 



Third instar. Fig. 32. The marginal wax tubes are not quite 

 uniform in size. They are arranged 14 on each lobe of the 

 head cephalad the eye, a single one on the prothorax just caudad 

 the eye, 15-16 on the wing pad of the mesothorax, 4-5 on the 

 wing pad of the metathorax and about 30 along each side of the 

 abdomen. 



Fourth instar. Pupa. Fig. 33. The marginal wax tubes 

 are vasiform and vary in size. Upon the head the wax tubes 

 are thickly situated over an area nearly the breadth of the eye. 

 There is one prothoracic marginal w^ax tube just caudad the eye. 

 The marginal wax tubes of the mesothoracic wing pad number 

 about 60 while others are present extending mesad, and the mar- 

 ginal tubes of the metathoracic wing pad number 10-12. On 

 the abdomen are about 60 marginal tubes and a thick triangular 

 area of dorsal tubes extending cephalad. 



The thorax and abdomen of the pupa are pale green with pale 

 yellowish brown broad transverse bands. The head is of a pale 

 yellowish brown tint, with dark eyes. The antennae hardly 

 reach the wing pads which are creamy white. Entire body with 

 a stiff but delicate white fringe of long wax filaments in an 

 unbroken and perfectly regular row. 



Cotypes collected on Amclanchicr canadensis (L.) Medic, in 

 July at Orono, Maine. (Lot 1238). 



APHIDIDAE. 



EDITH M. PATCH. 



Mindarus abictinus Koch. 

 (Schi::.oncura pinicola Thomas). 



On ]\\\y 12, 1909, the tips of white spruce, Picca canadensis 

 (Mill.), and balsam fir, Abies balsamea (L.) J\Iill., in the vicin- 

 ity of Orono were noticed to be very generally and very seriously 

 affected. No cause for the trouble could at that date be found. 

 In the growth of mixed young balsam fir and white spruce the 

 hew shoots of the fir were entirely killed, having withered after 

 making a growth of about one-fourth inch. The spruce tips 

 were much ruffled and in many cases also dead and it was sur- 

 mised that the same cause might be responsible for the trouble 

 of both these conifers. (Lot 759. Lot 760). 



It was not until May 25, 1910, however, that the explanation 



