488 P. W. CLAASSEN 
greatly and become twice or three times their natural diameter. Two 
heads, one heavily infested with the larvae of L. phragmitella, and the 
_ other uninfested, are shown in Plate XLV, 59. This is the appearance 
of the heads in the fall. During the winter and spring the uninfested 
heads lose all their seeds so that only the rachis remains, but the in- 
fested heads retain their seeds in the fluffy condition just described till 
the following summer, when the heads finally drop to the ground. A field 
in which the majority of the heads are heavily infested is shown in Plate | 
XLIX, 84. This photograph was taken in July, just about the time that | 
the new heads were forming. In the old heads, as well as in the newly | 
formed ones, these larvae were present. | 
The larvae overwinter in the half-grown stage in the head of the jet, 
the fluffy material of the fruiting spike being their protection. 
In the latter part of May or early June the larvae attain their full 
growth. Then, in the midst of the downy material, the larvae spin their. 
thin, tough, white cocoons and transform to the pupal stage. Many of the | 
larvae, leaving the heads, go down and bore into the stem of the cat-tail | 
plant, forming burrows which they line with silk; and there they pupate. 
In the laboratory, larvae were placed in vials containing little bunches 
of seeds from the head of Typha. The larvae spun cocoons in the vials’ 
and pupated. Some of the larvae bored into the cole lined the tunnels 
with a little silk, and then transformed. 
The average pupal stage lasts 29.4 days. This was ascertained from 
data on five individuals in the laboratory, as shown in table 7. Cocoons 
TABLE 7. DertTeRMINATION OF THE PupATION PrRIOD OF LYMNAECIA PHRAGMITELLA 
STAIN. 
Length 
Specimen Date of Date of of pupal 
pupation | emergence | period 
(days) 
Dero ee. A SN URIS MOLD Sn Acoma et At ee RPE June 4 July 1 27 
DCE BRAR RR eea Cre Mata pe IRR GRE eater RCL TE |e gen A June 63 |e seen 5% | 
OYA ene OA RTT 5 en Me orate nba ae A SLL ie ait May 30 July 1 32 
2 AP ie ol eA ome Me eat tated Ra ney aeRO Hiren eA cA ee May 31 July 3 33 
ye (2. 2 oe Soe SOMmMs SDESSE ree patch cet in resis Val ORT oe ae June 5 July 6 31 
Cee 5 Sapa ReE tre =, AMEMEn OIA R anlar totes tguel fy 1ae ene [a Be ca) aadhbiar) 4! June 28 24 
PNG) 41a Ro nen as Soe ene CSR Meme the, Mouse thee aicic Goa OT Gaia lded boo avo. 29.4 
» = 
