Representative letters to five foreign and colonial scientific entomologists have been gathered into this chapter, among other reasons to show the diversity of Miss Ormerod’s work, carried on in close touch and in the most agreeable relations, with the highest wide-world authorities on various specialised branches of her subject.
To Professor J. Ritzema Bos, Amsterdam.
Torrington House, St. Albans, England,
July 27, 1893.
Dear Dr. Ritzema Bos,—I have not written to you for a long time, partly because I had nothing of sufficient importance to allow me to submit it to you, but also because both my sister and myself had rather severe illnesses.
Enclosed I beg to send you some pieces of potato, which I think it is just possible may be infested by (or at least have now) some slight presence of Tylenchus devastatrix (eel-worm, fig. [47]). I received several tubers this morning from near Helensburgh, in Dumbartonshire, Scotland. Mr. Robert Howie, the sender, writes me that a large field recently dug up by him was very much damaged by being badly “scabbed” in the same way as the samples sent. But, when I came to examine the so-called “scabbed” parts after washing, the surface for the most part looked to me more as if it had been gnawed by some larvæ, than if it were a diseased state of coat. The skin of the potato is often left overhanging. I was going to suggest to Mr. Howie that he should search for Agrotis larvæ, or Melolontha (Cockchafer), grubs, but examining further at the end of one or two tubers, where the skin was still in its natural state, excepting small patches of what was as yet only a slight discoloured roughness, I found a few eel-worms. They were so few that they evaded me when using the higher power, but in one instance I thought I detected a bulb near the head end. I am afraid I may be taking up your time with what is of no importance; still I thought I should like to send you some pieces, and if the attack is one of any interest I would gladly forward more. The eel-worms I have seen are all anguilliform, the largest was about as long or longer than the largest T. devastatrix I have seen, the others were smaller. Mr. Rochford has been carrying on with great care and precision his experiments as to poisoning Heterodera radicicola (root-knott eel-worms, fig. [49]). He has tried about forty different applications—noting the amount given and the effect on the eel-worms and the plants. I certainly hope that a few will show successful results, but he is very careful, and is now going over his series of experiments a second time, that he may be quite certain before coming forward with statements of effects. As soon as I know anything of interest I shall be very glad to be allowed to tell you; Mr. Rochford has given me permission. I do not know as yet whether he will bring forward his results himself, or leave it to me to do. Pray believe me, with best thanks for all the kind assistance you give me.
Larva, pupa, and antenna of male ♂ and female ♀.
FIG. 58.—COCKCHAFER, MELOLONTHA VULGARIS, FAB.
September 7, 1893.
As I think that you have either returned home, or will soon be returning, I now (with your kind permission) send a few more of the “scabbed” potatoes, which it seemed possible might be infested by Tylenchus devastatrix. If it should be convenient to you at your best leisure to make any examination, and to let me know results, I am sure I need not say how acceptable your information would be, not only to myself, but to many interested in the cause of this external deformity. I send the potatoes in a little tin box by parcel post. Recently I have had rather an interesting observation of the little black, somewhat pubescent, “lady-bird” beetle, Scymnus minimus, as a feeder on Red spider, Tetranychus telarius. I have not been able to find any account of its life history, so I have had great pleasure in watching its progress from larval to imago state. It seems to me to be greedily carnivorous; after a few hours’ want of food during their journey to me, the larvæ set to work to feed on what they could pick up on the back of a leaf infested by red spider, as eagerly as sheep on fresh grass; and as I found one day only a single larva remaining of three or four confined together, I suspect it was this survivor who had reduced his brethren to the small remains which were all I found. The final changes were rapid, for the above happened on August 28th, and shortly after it had pupated, and yesterday I found the little black lady-bird in most active condition.