38 the sugar-beet wireworm. 



The Adult, 

 emergence of the adult. 



During the last few days before emergence the pupa becomes very 

 sensitive to Hght or contact, and when disturbed turns around in its 

 pupal cell by moving its abdomen. An attempt was made to ])hoto- 

 graph one during this state, but in the hour and a half it was exposed 

 it did not remain quiet long enough for an exposure to be made. 

 The abdomen is drawn in and out as if the beetle were tiying to break 

 the pu])al skin. This goes on for some time, often for more th|in a 

 day, and finally the pupal skin splits down the dorsum of the thorax 

 and is worked off. The beetle (PI. XVI), which has been quite active 

 in shedding its skin, now becomes quiescent, and folding its legs and 

 antennae as they were in the pupa, remains in the pupal cell. The 

 cast pui)al skin lies in the posterior end of the ])uj)al cell along with 

 the last larval skin, and helps form an obstruction between the pupal 

 cell and the old larval channel. The cast pupal skin is semitrans- 

 lucent white and thin, but at the same time quite tough. 



In two cases the legs of the beetle broke through the leg cases 

 before the pupal integument split down the dorsum. Neither of 

 these adults com])letely emerged, and after moving their legs feebly 

 for a few days they died. 



PERIOD OF EMERGENCE. 



The i)eriod of emergence of the beetle from the pu])a varies widely. 

 This was true both of those which were reared in -the laboratory and 

 of those pupae which were collected outdoors. Adults emerged be- 

 tween early August and October in the laboratory, and pupae from 

 the fields have given adults between the same dates. One pupa 

 from the field transformed to adult October 6. Mr. Russell observed 

 one adult emerge in the laboratory as late as October 17. 



Beetles disturbed during the fall are able to bury themselves and 

 live if they are not injured. Several which emerged in the laboratoiy 

 were constantly disturbed so they could be watched, but it seemed to 

 have no ill effects on them. 



ACTIONS DIRECTLY AFTER EMERGENCE. 



As soon as the j)upal skin is shed the adult, retaining the ])osition 

 it had held as a pupa, lies in the pupal cell. At first the ])eetle is a 

 little softer and lighter in color, but soon becomes hard and fully 

 colored. Smce none of the pubescence on its thorax or elytra has 

 been rubbed off, it api)ears grayish in color. At this time these 

 beetles are totally different in their actions than they are in the 

 spring, when they a])])ear on the surface, l)eing negatively heliotro])ic 

 and hiding under anything they can find or burrowing into the soil 

 when exposed to light. They also seek damp, cool quarters in 



