1910 



GLEANINGS IN BEE CULTURE 



177 



the body extract waste substances from such 

 of the body fluids as the blood, etc., and in 

 turn excrete these substances into the diges- 

 tive tract or the kidneys, or even, in the 

 case of sweat-glands, on the skin of the ani- 

 mal. Both secretions and excretions may 

 be the results of ct-11 activity. Of course, the 

 term excretion is frequently used to indicate 

 waste products which have never gone 

 through the cells but have passed through 

 the alimentary canal in an unaffected state; 

 that is not, however, cellular excretion. 



I may add that, by observation, dissection, 

 and microscopical examination these facts 

 cerning the origin of horey-dew and the na- 

 ture of the siphons or holes which were sup- 

 posed to secrete the same have been con- 

 firmed by me. 



Ottawa, Canada. 



» ' ^ ' * 



THE SOURCE OF HONEY-DEW. 

 Most of It is in the Nature of an Excretion. 



BY DR. E. F. PHILL'PS, 

 In charge of Apiculture, Bureau of Entomology, Wash- 

 ington. D. C. 



The article on p. 763, Dec. 15, by the dis- 

 tinguished Scotch bee- keeper D. M. Macdon- 

 ald, seems to call for further discussion of 

 this subject. The past season has been a 

 most remarkable one in bee-keeping on ac- 

 count of the excessive amount of honey-dew 

 gathered by the bees, and equally remark- 

 able by the scarci y of honey. The result is 

 that most bee-keepers have on hand a quan- 

 tity of honey-dew honey. Under such cir- 

 cumstances it is but natural that we should 

 desire to have as good an opinion of the prod- 

 uct as possible, for we want to eat it, and we 

 desire also to be able to sell it under a good 

 name. There are a few bee-keepers, how- 

 ever, who do not want the exact truth about 

 the matter, even if it is not what their wishes 

 might dictate. 



Honey dew is a general term, including 

 sweet substances from several sources. 

 There are many plants which have nectaries 

 outside the flower which tecrete honey-dew, 

 which is gathered by bees. Among these 

 may be mentioned the hau, of Hawaii (see 

 Bulletin 75, Part V. of the Bureau of Ento- 

 mology) ; cotton, some of the acacias, and 

 conifers. It is a mistake, however, to as- 

 sume, as Mr. Macdonald does, that this is a 

 characteristic ot the majority of plants from 

 which honey dew is gathered, for the great- 

 er proportion of honey-dew is not a plant se- 

 cretion but an insect product. 



Insect honey-dew is produced by various 

 hemiptera, among which may be mentioned 

 scale insects, aphids, and leaf-hoppers. The 

 production of enormous quantities of honey- 

 dew by a leaf-hopper in Hawaii is di cussed 

 in the bulletin referred to above. The insect 

 honey-dew with which we have had to con- 

 tend during the past season is derived from 

 scale insects and aphids, and only observa- 

 tion can decide whether this is an excretion 

 or a secretion from certain glands. 



First of all, it can be stated that Mr. Mac- 



donald is mistaken when he states that the 

 plants secrete a sweet liquid on which the 

 aphids come to feed. These insects, and 

 scale insects also, feed only from the inside 

 of the plant through sucking mouth parts. 

 It is not necessary to offer proof on this point 

 so well known to all entomologists. The 

 only question to be consider, d is whether 

 the sweet substance given off by these in- 

 sects is an excretion from the anus, or 

 whether it comes from certain glands through 

 nectaries. The popular belief has long been 

 that it is derived from the nectaries, and 

 popular science furnishes beautiful tales of 

 the '"milking " of aphids by ants. Such writ- 

 ings are not always infallible. 



Probably a large proportion of the honey- 

 dew gathered by the bees this past season 

 was derived from scale insects which have no 

 nectaries The honey-dew from this source 

 is a pure excretion. 



That the honf y dew of aphids is an excre- 

 tion and not a secretion can readily be proven 

 by any one interested enough to spend a few 

 hours watching a group of these interesting 

 insects. Drops of honey-dew will be seen 

 to appear at the anal end of the insects, and 

 then to drop as if forced from the body. This 

 fact was noted as far back as 1800, and since 

 that lime has been observed and recorded by 

 various entomologists. Another interesting 

 test will be to secure one of the insects, hold- 

 ing it by the head between the thumb and 

 finger and gently pinching it. Usually, if 

 the insect is well fed a drop of clear sticky 

 honey-dew will be forced out from the body 

 at the anal opening; and if pinched hara the 

 body juices will be forced out here, and also 

 out through the nectaries. 



Some groups among these insects will be 

 with long prominent nectaries, and others 

 will be found without nectaries or nectary 

 pores. 



The first group secretes or excretes from the 

 nectaries a very small amount of a white liq- 

 uid which is by many supposed to be the 

 honey-dew of aphids. Even if honey-dew 

 comes from the nectaries it is an excretion, 

 or the casting-off of the waste products of 

 meiabolism for the liquid so ejected is not 

 of use to the animal in any of its functions. 

 Prof. C P. Gillette, Canadian Entomologist 

 for 1907, p. 236, states that "Neither he nor 

 his helpers who have been observing the 

 Aphidx raiher carefully for a few years 

 PdSt have ever found honey-dew issuing 

 from the cornicles." 



Among the second group (having no nec- 

 taries or nectary pores) some species live in 

 galls formed on leaves; and often a gall, when 

 fully developed, will be half tilled with this 

 excretion, and the aphids are probably sav- 

 ed from drowning only by the waxy secre- 

 tion which is secreted by glands along the 

 dorsal surface of the body. The fact that the 

 species of this group do not have nectaries 

 or even nectaiy pores, and yet excrete a 

 large amount of honey-dew, is clear evidence 

 that among them the honey-dew is excreted 

 througn the anal opening. 



As the aphids usually feed on the under 



