ABUNDANCE OF LAUV.'E OF PVIUMEIS CARDUI. 61 



ABUNDANCE OF LAEViE OF PYRAMEIS CARDUI AT 

 IN STOW, NOKTH DEVON. 



By Paymaster-in-Chikf Gervask F. Mathew, E.N., F.L.S., F.E.S. 



I NOTICED hibernated P. cardui on almost evei\y bright day 

 from April 24th, when the first specimen was seen, until late 

 in June, and on June 8th I watched a female while she was 

 busy liiying her eggs upon a hirge plant of the spear-thistle 

 (Cricus ianceolatus) growing on the top of a high bank. On 

 June 20th I thought I would take a look round and see if I 

 could find any larvae, so hunted about for a likely spot, and 

 eventually came to a rough field on the side of a hill facing 

 south, where a quantity of thistles were growing — chiefly the 

 common field-thistle (C. arvensis), but also with them a good 

 many clumps of the spear-thistle — and in a short time I found 

 four small larvae, apparently about a week or ten days old. 

 These were easily seen, for as soon as they are hatched they 

 settle down on the middle of the upper surface of a leaf and 

 attack the cutic e, making little white blotches, over which they 

 spin a slight web, in which their pellets of black frass become 

 entangled or are purposely fixed by the larvae. As I could only 

 find these small larvae I thought it better to postpone any further 

 search for a week or two. However, these four larvae grew so 

 rapidly I went lo the same field again on June 27th, and then 

 found seventeen, some of which were already more than half 

 grown. From this time up to July 7tli — the day I took the last 

 — I usually noticed larvae whenever I was out walking and looked 

 for them both in this neighbourhood and near Bideford. I took 

 eighty altogether, and might have taken many more had I wished 

 to do so. Of course the half- and full-grown larvae make much 

 larger webs, and some of them draw the tips of the pointed leaves 

 together, mingle them with spines from the calyx or pappus of 

 the plaiit with bits of frass, and so form a kind of cave, which 

 becomes larger as the larvae grow, and into which they retire 

 when tliey are not feeding or when about to change their skins. 

 Others form a sort of pocket just below the calyx. I only noticed 

 the full-, or nearly full-grown larvae exposed on their food-plant 

 on one or two occasions, so fancy that in a wild state they must 

 feed chiefly at night, although those in condnement were often 

 to be seen feeding by day. Where they go to change to pupae 

 I do not know, for I was not able to lind any attached to the 

 thistles although I searched many scores of plants that had 

 recently been occupied by mature larvae, but there was no sign 

 of any either upon the stems of the plants or suspended from 

 the under sides of the large lower leaves. I fanc}' they must 

 wander a considerable distance from their food-plants before 

 finding a suitable place. In confinement they all attached them- 



