OF THE STATE ENTOMOLOGIST. 153 



chances of loss ; and the base of the stamens forming flattened, sticky 

 discs, placed in the best possible position for adhering to the head 

 parts of a moth or butterfly endeavoring to reacii the nectar. In all 

 these features, and others that might be mentioned, there is remark- 

 able adaptation ; and the flowers of many species, as they unfold their 

 petals, seem not only to invite, but to court and crave, the interven- 

 tion of some scaly-winged marriage priest of "glorious color and 

 glistening eye," who shall at once procure a suitor and perform the 

 nuptials. 



Yet here we have adaptation of the plant only, and, except in 

 one or two rare instances, as, for instance, in that of a Madagascar 

 Orchis (A?} ffrceoum sesquipedale), where the nectary is so deep that 

 its nectar can only be reached by a moth with a very long tongue, 

 our Orchids are not dependent for pollenation on any one Lepidop- 

 terous species, but may be aided by many which have tongues of suf- 

 ficient length. Our Yuccas, on the contrary, seem to depend for 

 assistance, so far as we now know, on the single little Tineid which I 

 have described, and, for this reason, are among the most interesting 

 of entomophilous plants. At least such is the case with the capsule- 

 bearing species, i. e., those which have dry, dehiscent pods ; and I 

 will here premise that ray observations have been made* upon a fila- 

 mentose-leaved species in common cultivation about St. Louis, and 

 which Dr. Engelmann takes to be Y. jyuherula or Y. glauca. 



Dr. Engelmann has made some interesting observations on the 

 fertilization of Yucca,t and to him I am indebted for drawing my 

 attention to the fact that the plants of this genus must rely on some 

 insect or other for fertilization. The sagittate anthers open a little 

 earlier than does the perianth, and expel the pollen grains, which, 

 being glutinous, remain attached in different sized lumps to the inside 

 of the flower. The stigmatic tube contains nectar, and is connected 

 with the ovarian cells, and the pollen must be introduced into the 

 tube, but can not be so introduced without artificial aid. 



There are several insects that frequent our Yuccas about flower- 

 ing time. Some, doubtless, feast on the pollen, while others feed 

 either by gnawing into the young fruit or pumping the juices there- 



*Tlie fructiflcation of such Yuccas as bear fleshy, pulpy fruit, of which Y. aloifolia may be taken 

 as the type, has not been studied; but, even with this hist-mentioned species, the facts, so far as 

 known, strongly indicate i\\i\t Pro nub a is principally if not solely instrumental in bringing it about. 

 Its seeds are infested with our Promtba larva, though not to the same extent as those of the dehiscent 

 species. It would be prematui-e to speculate until we have further facts ; but it is not at all unlikely 

 that the seeds of the fleshy pods are less congenial to the larva?, and that a smaller percentage is pro- 

 duced from the eggs consigned to such pods by the moth. In addition to the Pronuba larva in the seeds, 

 the fruit of I', aloifolia nourishes a smaller, white, apodous larva, which is found in the pulp, some- 

 times in considerable numbers. It may be traced from slight depressions on the outside, and shows 

 Hymenopterous afllnities. It occasionally gnaws into the seed from the outside, but its legless char- 

 acter will at once d stinguish it from the larva of Pronuba, which will be described further on. 



tSee Bulletin of Torrey Botanical Club, Vol. Ill, No. 7. 



