This is a good example of a leap in a haiku. We have two parts “spiderweb dew” and “I read an old letter.” The leap the writer makes in seeing the relationship between the two parts make a third part in the reader’s mind.
The third part to me is about the irrelevancy of the dew on the spiderweb and the emotional power behind reading an old letter, and how these relate. The dew, while beautiful, is something unneeded on the spiderweb, and the spider would rather have a nice fly. The old letter on the other hand, is probably from a loved one, and the writer wants to experience something again, to renew a part of his or her life, even for a moment. This brevity is connected to the dew poignantly, which only comes for a few hours in the day.
The connection between the two images could also infer that the past is not so important as we may believe, and that it is simply “spiderweb dew.”
To get to the image, the colors are striking. I believe the blue signifies the emotion of reading the letter. It is like a modernist painting, with colors that wake you up to the present.
Note: When haiku is accompanied by art, it is called haiga.
– Nicholas Klacsanzky