This is an action based on diversity of citizenship, 28 U.S.C. § 1332 . Plaintiff is a citizen and resident of the State of Idaho, and the defendant is a resident and citizen of the State of Washington. The matter in controversy exceeds, exclusive of interest and costs, the sum of $10,000.00.

The plaintiff appeals from a judgment in favor of the defendant based upon a jury verdict in his favor, and the order of the District Court denying plaintiff’s motion for judgment notwithstanding the verdict of the jury, or, in the alternative, for a new trial.

It is stated as an admission of fact in the pre-trial order “That on or about June 16, 1960, Gene Shipp, then six years of age, in company with his older brother, Jackie, and his mother, was in the store of the defendant in Cashmere, Washington, as a business invitee. As Gene Shipp was leaving the store, he sustained injuries caused by the breakage of glass installed in the North exit door of the store.”

The complaint charged that the defendant failed to exercise reasonable care for the safety of plaintiff by not providing glass panels in the exit door of the market of sufficient strength and thickness, and that such negligence was the proximate cause of plaintiff’s injuries and damages. Defendant, in his answer, denied negligence on his part and as an affirmative defense alleged negligence on the part of plaintiff which proximately contributed to the accident and the resultant injuries.

Plaintiff specifies as errors on this appeal the refusal of the District Court to instruct the jury that because of plaintiff’s age he was conclusively pre sumed to be incapable of acting negligently, and the giving by the District Court of the following instructions on contributory negligence:

The exceptions or objections taken by the plaintiff before the District Judge are in the following form:

Since no issue has been raised on this appeal as to the sufficiency of the evidence produced by plaintiff to take the question of defendant’s negligence to the jury, the only questions presented to us on this appeal are:

1) Is a child of six years of age conclusively presumed incapable of negligence ?

2) If the District Court correctly instructed the jury that, in the case of a child of the age of six years, there is a prima facie presumption against his being capable of contributory negligence which presumption prevails unless overcome by evidence in the case, was there before the jury sufficient evidence for the jury to find that the prima facie presumption had been overcome?

Since Federal jurisdiction in this case is based upon diversity of citizenship, the law of the State of Washington governs. Rules of Decision Act, 28 U. S.C. § 1652; Summers v. Wallace Hospital, 276 F.2d 831 (9th Cir. 1960).

’ The latest expression by the Supreme Court of Washington which has been called to our attention dealing with questions under review on this appeal is Cox v. Hugo, 52 Wash.2d 815 , 329 P.2d 467 (1958). In that case the injured child was five years and eight months of age. The question before the Supreme Court was whether the lower court had correctly decided that the child in question was conclusively presumed to be incapable of negligence. In the course of its opinion the Supreme Court states:

While many earlier cases of the Supreme Court of Washington are cited to us in the briefs involving the application of the doctrine to children of varying ages, we deem it unnecessary to review them in this opinion. In light of the language of the Cox case, and giving weight to the fact that the learned District Judge was an active practitioner in the State of Washington prior to his appointment, we are of the view that the District Court correctly and properly refused to instruct the jury that a child of six years of age is conclusively presumed to be incapable of negligence.

We now consider the propriety of the action of the District Court in submitting the issue of contributory negligence to the jury.

The rule appears to be well established in the State of Washington that contributory negligence, being an affirmative defense on which the defendant has the burden of proof, the defendant must produce substantial evidence of the plaintiff’s own negligence before the trial court is required to instruct the jury on contributory negligence. Jackson v. City of Seattle, 15 Wash.2d 505 , 131 P.2d 172 (1942); Schneider v. Midwest Coast Transport Inc., 51 Wash.2d 673 , 321 P.2d 260 (1953).

It is reversible error in the State of Washington to instruct the jury on an issue which is not supported by substantial evidence. Hughey v. Winthrop Motors Co., 161 Wash.Dec. 225, 377 P.2d 640 (Jan. 10, 1963); Rehearing denied Mar. 21, 1963.

In the Hughey case the Supreme Court stated:

In the instructions which we have quoted, the District Court informed the jury that it was the duty of the minor plaintiff “to exercise the same care that a reasonably prudent minor of the same age, intelligence and experience would exercise under the same or similar circumstances,” and there existed “a prima facie presumption against his being capable of contributory negligence, which presumption prevails unless overcome by evidence in the case.” From our review of the record we are compelled to say that the defendant failed to sustain the burden which was on him to overcome by substantial evidence the prima facie presumption and therefore that the District Court erred in submitting to the jury the instructions on contributory negligence.

In the instant case no affirmative evidence was offered by the defendant on the issue of contributory negligence of the plaintiff as such evidence relates to the age, intelligence and experience of the plaintiff, but in this respect defendant relies entirely upon the testimony given in the plaintiff’s case in chief by the father and mother of the plaintiff and cross-examination thereof.

There is no evidence in the record that by reason of his age, intelligence or experience the minor plaintiff should have been aware of or should have appreciated the danger to him in running into the glass door with his hands upraised. There is no evidence that the minor plaintiff had any knowledge of, or warning concerning, such danger. The only testimony upon which the defendant relies to sustain the action of the District Court is extremely meager, consisting of the testimony that the minor “was a very, very bright and well-mannered boy” and that “he is a pretty good student, I mean pretty good intelligence,” and that “he enjoys taking the toys apart, you know that has the little clamp deal on it and looking inside of them and seeing just how they are made, and he does very well for a kid his age.” Evidence discloses that the minor plaintiff had lived his life in rural areas; that he had not attended school [either primary or kindergarten] at the time of the accident, although the minor plaintiff knew his A, B, C’s. There is no evidence of any familiarity on the part of the minor plaintiff with glass doors, or of any knowledge on his part of any danger appearing therein.

The judgment and order appealed from are reversed and the cause remanded to the District Court with instructions to grant plaintiff a new trial.