INSECTS ATTACKING WEEDS IN ^MINNESOTA. 149 



Larva. — Length, al)out 9 mm. The hooks of the prolegs num- 

 ber about eighteen, arranged in a circle, with small and large ones 

 alternating. 



This species was also reared as a leaf miner in Solidago canadensis. 



BURDOCK (Arctium lappa L.j Insects. 



The Burdock Seed Caterpillar (Mctzncria lap pel la, Linnj. 



This caterpillar is very common in the seeds of burdock wher- 

 ever found. The larvae are stout and the legs are so short that 

 they appear lacking, giving the larva very much the appearance of 

 that of the weevil type. For this reason, I was at first continually 

 surprised to get only moths from the seeds. For some reason or 

 other, perhaps lack of moisture, some of the over- wintering larvae 

 did not transform, even until late the following fall, although they 

 were alive all of the time. (Jn June 23, pupae were still present 

 in the seeds. The larxae consume the seeds, eating their way from 

 one seed to the other. 



ROADSIDE THISTLE (Cirsium discolor (Aluhl.) Spreng.) Insects. 

 The Roadside Thistle Miner ( Agroniyca zirens, Loew). 



This species is also said to mine in the roots of clover. Lafay- 

 ette, Indiana ( F. M. Webster) and in the stems of Ambrosia arte- 

 misiifolia. L. Annals Ent. Soc. Amer. \T:321. 



Life History. — ( )n June 4, the insect was still in the pupal 

 stage. Full-grown larvae were found August 24 mining in the 

 stem about level with the ground and for a short distance above 

 the ground. Altho as many as 15 or 20 may be present in a single 

 stem, the plant appears perfectly healthy. There is apparently one 

 generation a year and the winter is passed in the pupal stage. The 

 egg and the method of ovi])osition has not yet been observed. 



Larva. — Length. 5 mm. x 1.2 mm. wide. Elongate, cream- 

 white in color, except for the mouth-hooks and anal plates, which 

 are black. Nearly uniform in diameter, except at the ends. Two 

 great hooks, one of wdiich appears situated above the other. The 

 anterior spiracles are located near the mid-dorsal line and end in 

 about 6 or 7 lobes. Two very minute tubercles situated beneath 

 each anal plate. The stigmal plates are elliptical and about their 

 shorter diameter apart, each plate ending in about 1,"^ or 16 pores. 

 A stout black hook projects dorsally from each plate. 



