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THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



and ants, whose industry, instincts, and intelli- 

 gence confound our reason. 



We have remarked the rule : those beings 

 gifted with the finest organization have progeny 

 too weak to be safely left to themselves ; there- 

 fore the parent cares for them. But the rule has 

 its exceptions. Some species, quite like those 

 that are most remarkable for their industry, do 

 not know how to do anything for their young, 

 and yet their offspring at the beginning of life 

 require assistance every moment. An impeiious 

 want to be satisfied on one side, absolute impo- 

 tence to help on the other — this is the problem 

 of which the solution is found by the aid of a 

 special instinct bestowed on mothers unable to 

 work for their progeny. When one cannot rear 

 one's children, they are confided to strangers — 

 nothing is simpler. The bird called the cuckoo is 

 well known, and very curious stories are still told 

 about it, sometimes without distinguishing between 

 old legends and the accounts of careful observers. 

 The cuckoo, which is constantly heard in large 

 woods and hardly ever seen, from its extreme 

 shyness, builds no nest, as every one knows. 

 Unable to construct one, it goes and drops its 

 eggs in the nest of some other bird. The reason 

 of that incapacity eludes us, for till now no 

 known peculiarity of its organism has furnished 

 an explanation. Yet a very curious observation 

 has been made : the members of the two sexes 

 are very unequal ; there are fifteen or twenty 

 males for a single female. In this crowd of suit- 

 ors the female, it would seem, wishes to please 

 all, and her incessant gallantries must divert her 

 from any maternal duty. The cuckoos, then, se- 

 cretly carry their eggs to the nests of different 

 birds — the red-throat, the nightingale, the red- 

 wing, the peewit, and many others besides — and 

 these birds, if they do not detect the cheat, 

 hatch the alien egg, and, after it is hatched, rear 

 the intruder as one of their own brood, notwith- 

 standing its size, which soon grows beyond that 

 of the rightful young, and becomes very danger- 

 ous to them. If we are to believe some asser- 

 tions, the female cuckoo never wholly loses the 

 feeling of maternity : she does not leave the 

 neighborhood of the places where her young are 

 reared till after they have quitted the nest. 



Some insects behave nearly like the cuckoo. 

 The great downy humblebees, sometimes red, 

 sometimes black, with some parts yellow, tawny, 

 or reddish, so common in the fine season about 

 the flowers in the fields or the edge of the woods, 

 are wonderfully industrious creatures, as we 

 know, and take the most irreproachable care of 



their progeny. Besides these laborious insects, 

 we find species incapable of any care, and so like 

 the true bumblebee in their appearance and 

 principal marks that painstaking naturalists had 

 not been able to distinguish the two kinds ; but 

 one day an observer, Le Peletier de Saint-Far- 

 geau, more attentive than his predecessors, re- 

 marked a significant difference : these species, 

 hitherto confounded with humblebees, are quite 

 wanting in working-instruments ; their legs have 

 no sack to store the pollen, no prickles to attach 

 the flakes of wax ; the first joint of their tarsi, 

 though quite broad, yet is not such a plate as the 

 humblebees use, like a trowel, and carries no 

 hairy tuft suited to brush off the collected pol- 

 len. No working tools means evident inability 

 to build, and also impossibility of feeding the 

 larvae. These insects, designated by the name 

 of psithyres, have recourse to the humblebees 

 for the preservation of their own species. There 

 is a simple explanation of the resemblance given 

 by Nature to these two kinds of creatures. The 

 cuckoo, smuggling an egg into a small bird's 

 nest, has no reason to fear being at a disadvan- 

 tage if caught in the act by the owner. It is not 

 the same with the insect that makes its way into 

 the bumblebee's nest. The habitation is always 

 more or less filled and guarded by individuals 

 whose sting is mortal. The best-managed trick 

 would fail. Here the insect must deceive as to 

 its kind, and seem a humblebee when it is not 

 one. The psithyres, therefore, have received the 

 gift of the size, shape, colors, and complete ap- 

 pearance of the bumblebee, and as there are of 

 the latter quite a large number of species known 

 apart by their colors, so there are psithyres an- 

 swering to the characteristic peculiarities of these 

 different species. Seeing cne of them, we may 

 say, without fear of mistake, this is the parasite 

 of that particular humblebee. The psithyre 

 then enters, without being disturbed, the dwelling 

 where they are working and bringing up the 

 young insects ; its dress makes it pass for a 

 member of the family ; it goes in confident that 

 it will not be recognized as a stranger nor mal- 

 treated. In the cells built in view of a different 

 purpose it deposits its eggs ; the grubs that will 

 come from them will have all the appearance of 

 those of the humblebees, and the latter will 

 make no difference in their nursing. Thus a re- 

 lation is perpetuated between two species not 

 belonging to the same genus. The humblebees 

 could very well dispense with the psithyres, but 

 the latter would inevitably perish by the disap- 

 pearance of the former. 



