Leroy Knotts and Darryl Petschen appeal from their convictions of conspiring to manufacture controlled substances. The principal issue on appeal concerns the admissibility of evidence obtained through use of a signal transmitter (“beeper”) placed by police agents in a can of chloroform purchased by a co-conspirator of the appellants’. Knotts and Petschen argue that the war-rantless use of this beeper violated their Fourth Amendment rights, and that the evidence obtained through tracking the beeper should have been excluded by the district court.
Knotts and Petschen were part of an enterprise engaged in the manufacture of amphetamine or methamphetamine. A third member of this enterprise was Tristan Armstrong, the “chemist” of the group, who was indicted with the appellants but pleaded guilty and testified against them. In June of 1979, Armstrong had drawn the suspicion of Minnesota investigators by his alleged pilferage of drug-precursor chemicals from 3M, his former employer. Further investigation of Armstrong raised suspicion of illicit drug manufacturing, and produced evidence linking Armstrong to appellant Petschen. Armstrong was placed under surveillance and seen taking boxes from the Hawkins Chemical Company in Minneapolis to Petschen’s house in that city. Petschen in turn took the boxes to a farmhouse in Scandia, Minnesota, where they were unloaded.
Despite the apparent success of visual surveillance, police agents took the further step of using electronics. On February 28, 1980, Minnesota agents delivered to the Hawkins Chemical Company a can of chloroform in which a beeper had been placed with the company’s consent. As expected, Armstrong picked up the can later that day. Police followed Armstrong to Petschen’s house, where the can was transferred to Petschen’s car. Petschen was followed to his Scandia farmhouse, where he stopped only briefly before driving on. The agent following Petschen twice lost sight of Pet-schen’s car, once purposely when Petschen, perhaps aware that he was being followed, began driving evasively. Shortly after this evasion the agent lost the beeper signal, and the drum’s location was uncertain until the signal was again picked up and its source verified through the use of a helicopter. The drum was stationary at a spot later found to be in the yard of a secluded cabin owned by appellant Knotts.
Four days later, Minnesota and federal agents got and executed warrants to search Petschen’s farmhouse and Knotts’ cabin. The search of the cabin uncovered a clandestine drug laboratory. Chemicals and equipment seized from this laboratory were admitted into evidence over Knott’s and Petschen’s motions to suppress.1
The Fourth Amendment is currently described as protecting persons’ “legitimate expectations of privacy” from government’s unreasonable intrusions. See Rawlings v. Kentucky, 448 U.S. 98, 103-105, 100 S.Ct. 2556, 2561-62, 65 L.Ed.2d 633 (1980); United States v. Salvucci, 448 U.S. 83, 89-91, 100 S.Ct. 2547, 2552-53 (1980); Rakas v. Illinois, 439 U.S. 128, 139-49, 99 S.Ct. 421, 428-433, 58 L.Ed.2d 387 (1978). Such intru*517sions are unreasonable if the applicable cause or warrant requirements are not met. E. g., Katz v. United States, 389 U.S. 347, 356, 88 S.Ct. 507, 514,19 L.Ed.2d 576 (1967); Rawlings, supra, 448 U.S. at 113, 100 S.Ct. at 2565 (Blackmun, J. concurring).
The difficulty in applying the test of “legitimate expectations of privacy” in electronic surveillance cases is that consideration of such expectations leads almost ineluctably to the “philosophical question” whether the constitutional protections of privacy must or should diminish with technological innovations in surveillance. See United States v. Bruneau, 594 F.2d 1190, 1196 (8th Cir.), cert. denied, 444 U.S. 847, 100 S.Ct. 94, 62 L.Ed.2d 61 (1979). The Court in Bruneau was reluctant to address this sweeping question. It limited its decision to the narrow question before it, and we will follow this judicious lead.
The narrow preliminary issue in this case is whether the monitoring of a beeper placed in an item of non-contraband personalty can be a search subject to the Fourth Amendment’s restrictions.2 This is' not a case of a beeper being attached to an automobile, so the ultimate issue is not whether there can be an expectation of privacy in the route taken by an auto over public roads. Cf. United States v. Michael, 645 F. 2d 252, 257 (5th Cir. 1981) (en banc, 11-3-10 decision) (plurality relied on the diminished expectation of privacy surrounding automobiles), cert. denied, - U.S. -, 102 S.Ct. 489, 70 L.Ed.2d 257 (1981); United States v. Moore, 562 F.2d 106, 112-13 (1st Cir. 1977), cert. denied, 435 U.S. 926, 98 S.Ct. 1493, 55 L.Ed.2d 521 (1978) (“probable cause” sufficient to justify warrantless electronic tracking of car on public roads); United States v. Hufford, 539 F.2d 32, 34-35 (9th Cir.), cert. denied, 429 U.S. 1002, 97 S.Ct. 533, 50 L.Ed.2d 614 (1976) (used same rationale as Michael plurality).
The Circuits that have considered the constitutional strictures on tracking beepers placed, not on vehicles, but on other personalty, have reached varying results. Numerous courts have seen no legitimate expectation of privacy in the movement of illicit drugs discovered in international mail. See United States v. Bailey, 628 F.2d 938, 942 (6th Cir. 1980), and cases cited there. The chemical tracked in this case is not contraband. It would be a limitless expansion of police power to allow warrantless tracking of lawful goods wherever an illicit use was suspected. If crime is suspected, cause for electronic surveillance of any private area or activity should be determined by a neutral magistrate, not by interested executive agents. See Bailey, supra, 628 F.2d at 944.
The First and Sixth Circuits have held that if an object is placed in a “private area,” Bailey, supra, 628 F.2d at 944, or “withdrawn] from the public view,” Moore, supra, 562 F.2d at 113, beeper surveillance of the object’s location or movement is an infringement of legitimate privacy interests. As such this surveillance is subject to the warrant or cause requirements of the Fourth Amendment. The Ninth and Tenth Circuits, on the other hand, have formulated what might be called a de minimis exception to the Fourth Amendment, holding that since the intrusiveness of beepers is slight, beeper surveillance does not require the antecedent justification of a warrant. See United States v. Clayborne, 584 F.2d 346, 350-51 (10th Cir. 1978)3; United States v. Dubrofsky, 581 F.2d 208 (9th Cir. 1978), followed, United States v. Bernard, 625 F.2d 854, 859-60 (9th Cir. 1980).
*518The decisions of the First and Sixth Circuits are more persuasive. Expectation of privacy is the touchstone of Fourth Amendment protections, and expectations of privacy do not depend on the artfulness and suavity of the invasive means of government agents. In the present case the beeper’s signal led police agents to a drum of chloroform beneath a wooden barrel in the yard of a remote rustic cabin. This cabin was not found by watching or tracking the “public” progress of Petschen in his car. Agents lost both natural and electronic “sight” of Petschen and did not again pick up the signal from the bugged container until the container was stationary and out of public view at the cabin owned by Knotts.
The argument raised by the government, that “use of a beeper to monitor the path of an object contemplates use of a beeper to determine its final resting place” proves too much in this case. As noted above, a principal rationale for allowing warrantless tracking of beepers, particularly beepers in or on an auto, is that beepers are merely a more effective means of observing what is already public. But people pass daily from public to private spheres. When police agents track bugged personal property without first obtaining a warrant, they must do so at the risk that this enhanced surveillance, intrusive at best, might push fortuitously and unreasonably into the private sphere protected by the Fourth Amendment. It did so in this case, where the beeper’s signal was lost and found again only after the beeper-laden drum was on private property out of public view.
Knotts, as the resident of the property, could certainly have a reasonable, legitimate expectation of privacy in the kind and location of objects out of public view on his land. With Petschen, however, this is not so. Petschen asserts that he had a reasonable expectation of privacy in articles left at Knotts’ farm because he was a co-venturer of Knotts’ and had a “possessory and proprietary interest in the laboratory equipment, chemicals and in the laboratory which he set up and operated.” Although Petschen might have had a subjective expectation of privacy in the equipment of a clandestine drug laboratory on his coconspirator’s property, this is not an expectation “that society is prepared to recognize as ‘reasonable.’ ” Rakas v. Illinois, supra, 439 U.S. at 143 n. 12, 99 S.Ct. at 430 (quoting Katz v. United States, 389 U.S. at 361, 88 S.Ct. at 516 (Harlan, J., concurring)). The evidence obtained from the search of Knotts’ cabin was admissible against Petschen, but not against Knotts.
The appellants’ second contention, that there was a fatal variance between the indictment and proof in their cases, is not persuasive. The indictment charged conspiracy to manufacture “controlled substances, including but not limited to, [s/c] methamphetamine. ...” The evidence at trial tended to show conspiracy to produce amphetamine, not methamphetamine. Amphetamine is also a controlled substance, so there was no variance from the indictment’s charge. Even though the proof did vary from the superfluous example of a controlled substance given in the indictment, that variance did not affect “substantial rights” of the appellants.1 See Fed.R.Crim. Pro. 52(a).
For the reasons set forth above, appellant Petschen’s conviction is affirmed; appellant Knotts’ is reversed.
. The search of Petschen’s residence also uncovered precursor chemicals and incriminating documents. On appeal, Petschen does not question the validity of the warrant to search his house.
. Another preliminary issue is whether installation of the beeper violated constitutional protections. Following Bruneau, we hold that the consent of the owner at the time of installation meets the requirements of the Fourth Amendment, even if the consenting owner intends to soon sell the “bugged” property to an unsuspecting buyer. See 594 F.2d at 1194. Caveat emptor.
. Clayborne also suggests that the area invaded by the use of the beeper in that case was open to the public, although the only information offered to support that conclusion was that the building housing the clandestine laboratory in Clayborne had several entrances. See 584 F.2d at 350 n.2 and accompanying text.