303 



THE ACTS OF POLLINATION AND OVIPOSITION. 



riaviiiii' thus drawn attention t(>tlK' most characteristic structures of 

 Pronuba, we shall better understand the following account of the acts 

 of imllinntion and oviposition which I quote from an article recently 

 prepared for the Annual lieport of tlu' Missouri Botanic Garden: 



Tlioniili ;ill the acts <if the female are nocturnal, it is 

 not at all (liflicnlt to Ibllow them with a laDtern, for, 

 alheit ordinarily shy, she may be closely approachefl 

 when altout to ovii>osit. Her activity begins soon after 

 (lark, but consists, at first, in assiduously collecting a 

 load of pollen. She may be seen running np to the top 

 ol one of the stamens and bending her head down over 

 the anther, stretching the maxillary tentacles, so wonder- 

 fully modified for the purpose, to their fullest extent, 

 the tongue uncoiled and reaching to the opposite side 

 of the stamen (Fig. 61). In this manner she is "ibie to 

 obtain a firm hold of the stamen, while the nead is 

 kept close to the anther and moved peculiarly back and 

 forth, something as in the motion of a caterpillar when 

 feeding. The maxillary jialpi are nsed in this act very 

 much as the ordinary mandibles are nsed in other in 

 sects, removing or scraping the pollen from the anthers 

 toward the tentacles. After thus gathering the pollen 

 she raises her head and commences to shape it into a 

 little mass or pellet by i>sing her front legs, very much 

 as a cat does when cleansing her month, sometimes using 

 only one leg, at another time both, smoothing and press- 

 ing the gathered pollen, tl«e tentacles meanwhile stretch- 

 ing an<l curving. After collecting all the pollen from 

 one anther she proceeds to another and repeats the 

 operation, then to a third and fourth, after which, 

 with her relatively large load — often thrice as large as 

 the head— held firmly against the neck and front trochan- 

 ters, she usually runs about or flies to another plant; for I have often noticed that 

 oviposition, as a rule, is accomplished in some other flower than that from which 

 the pollen was gathered, and that cross fertilization is thus secured.' 



Once fnlly equipped with this important commodity, she may be seen either 

 crawling over or re.sting within the flower, generally with the head toward the base. 

 From time to time she makes a sudden dart and deftly runs around the stamens, and 

 anon takes a position with the body betw<'en and the legs straddling two of them, 

 her head being usually turned toward the stigma. A-* the terminal portion of the 

 stamens is always more or less recurved, she generally has to retreat between two 

 of them until the tip of her abdomen can reach the pistil. As soon as a favorable 

 point is reached, generally just below the middle, she rests motionless for a short 

 time, when the abdomen is slightly raise<l and the lance-like ovipositor is thrust into 

 the soft' tissue, held the best part of a minute, while the egg is conducted to its 

 destination, and then withdrawn by a series of up-and-down motions. 



Fig. 61.— Female Pronuba 

 yuccagella gathering pol- 

 len, — ;■ 5/ 



' The actions here described are sometimes quite deliberate, but often they are too 

 rapid to lie analyzed, and the running to the top of the stamen and the motion of 

 head in gathering the pollen are in time and manner much the same as in thrusting 

 the pollen into the stigma. 



