Read before Mich. Agri'l Col. Nat. His. So'y, June 20. 



Honey Dow on the Tamarack. 



PROF. A. J. COOK. 



During the last week of May, 1879, 

 the American larch or tamarack, stand- 

 ing near the house occupied by Prof. 

 Beal, was discovered to be swarming 

 with bees. Upon closer inspection the 

 needle-shaped leaves were discovered 

 to b » thickly dotted with drops of thick 

 viscid nectar. Many of these drops 

 were sufficiently large to enable one to 

 test the .uality of their saccharine ele- 

 ment. The sweet was very pleasant, 

 much like that of syrup made from 

 granulated sugar. The drops were clear, 

 colorless and not unlike dew drops in 

 t^eir appearance. 



I closely examined the twigs for 

 plant lice, but lookf i in vain. I only 

 examined the lower limbs which could 

 be observed from the ground. 



Two weeks after I received larch 

 twigs from A. A. Winslow, New Hol- 

 stejn,Wis., with a letter stating that 

 the tree from which the twigs were 

 taken was full of large drops of beau- 

 tiful honey, which the bees were very 

 rapidly storing in the honey boxes. 

 Upon examining these twigs I found 

 them well sprinkled with grains of su- 

 gar. The sugar was very white and 

 tasted very much like our best granu- 

 lated sugar. Mr. Winslow also in- 

 closed leaves of deciduous trees which 

 were under the tamarack boughs. These 

 were coated with sugar, and appeared 

 as if they had been dipped into a con- 

 centrated syrup of coffee sugar, and 

 then allowed to dry. 



Here, then, it seemed that we had a 

 veritable case of honey dew, not from 

 insect secretion, but an exudation from 

 the leaves. For the past four weeks I 

 have repeatedly examined the twigs of 

 the larch, each time to find the drops 

 of nectar, but each time failed to find 

 any lice, until early the present week 

 when I found even' on the lower twigs 

 the tamarack louse, Lachnus caricifex 

 Fitch. But I had found the nectar be- 

 fore the lice, and when there were only 

 hundreds of lice, there were millions of 

 nectar drops. The lice too were of the 

 genus Lachnus, with short imperforate 

 nectaries. How improbable then, that 

 the nectar owed its origin to the lice. 

 Yet the presence of the lice so clouded 

 the evidence that I did not feel satis- 

 tied. I examined the epidermis of the K 

 leaves taken from just below a drop of 

 nectar, with a high power microscope, 

 but could find no pore or opening from 

 which the sweet might have exuded. I 

 then examined the clover leaves be- 



353 



neath^theftree and found them thickly 

 dotted with the same viscous drops of 

 nectar, which the .ants were rapidly 

 sipping up, showing that the drops 

 must have fallen recently. Yet the 

 consistency of the nectar would have 

 prevented it from falling off the leaves. 

 I washed all the leaves of a twig by 

 use of a small camel's hair brush free 

 of the nectar. This twig contained 

 lice, and was carried to my study, 

 Soon the leaves near the lice were well 

 sprinkled with the nectar. I next sus- 

 pended a twig, with several lice upon 

 it, above a paper and collected upon 

 the surface of the latter several drops 

 of the sweet. I then pressed some of 

 the lice when there oozed out, not of 

 the nectaries, the place where the sweet 

 fluid is seen to exude from lice of the 

 genus Aphis, but out of the vent a sub- 

 stance which was clear, viscid ; yes, and 

 sweet, for I tasted of it. Why not as 

 well take it direct from the lice as to 

 receive it at second hand .through the 

 kindly office of the bees ? I next looked 

 with a good lens at a group of lice for 

 some time, when I saw a drop of nectar 

 shoot out for some distance and fall to 

 the ground. 



This sweet, then, is certainly a secre- 

 tion or excretion from the American 

 larch louse. This louse is about one- 

 eight of an inch long ; is brown, with 

 a whitish dorsal line, and a band of the 

 same color across the abdomen ; be- 

 tween each segment, on each side of the 

 white line, are three rows of black dots. 

 The under surface of the body is light 

 yellow speckled with white. The feet 

 and antennae are of the same color, 

 with more or less of black. The rudi- 

 mentary nectaries are black. The beak 

 is long and pointed ; the legs long, and 

 few lice make better use of their legs. 

 In a few minutes a louse will pass over 

 as many feet, so that the failure to find 

 one on a twig is no sign that one might 

 not have been there within a short 

 time. 



These lice are exceptionally civilized, 

 as they seem to preserve the family re- 

 lation. About each whirl of leaves may 

 be seen the mother with her little fam- 

 ily, of usually four, each busily em- 

 ployed working its own little force 

 pump. Like all plant lice these lit- 

 tle ones are fatherless at this season, 

 and surely the mother louse is to be 

 congratulated in that she has the abil- 

 ity to keep the family together. Soon 

 each of the offspring marches forth to 

 begin housekeeping for itself, becomes 

 a squatter, and soon rejoices in its own 

 little family. 



Upon dissection I found each ovovi- 

 viparous louse to contain four or five 



